FiiO K15 – Streamer Desktop DAC & Headphone Amplifier with Dual AK4497S

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FiiO K15 – Streamer Desktop DAC & Headphone Amplifier with Dual AK4497S

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Desktop DAC and Headphone AmplifierHigh-end AKM DAC AK4497$*2 | Discrete Class-AB transistor current-boosting headphone amplifier circuitTwo ultra-low phase noise femtosecond... Read more

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Description

Desktop DAC and Headphone Amplifier
High-end AKM DAC AK4497$*2 | Discrete Class-AB transistor current-boosting headphone amplifier circuitTwo ultra-low phase noise femtosecond crystal oscillators]3000mW++3000mW powerful outputDAC and headphone amp · Streaming media · Local playback | Fully balanced audio circuit3.93-inch touchscreen | infrared remote control included 2.4G/5G dual-band WiFl + Gigabit Ethernet.

The Fii0 K15 is a flagship-grade, fully-featured desktop DAC (Digital-to-AnalogConverter)and headphone amplifier. lt isdesigned to be the central hub of a high.end personalaudio system,combinincstate-of-the-art components, massivepower output,and extensive connectivitvoptions into a single, sophisticated unit
Key Features & Description
1.Uncompromising Core Architecture Dual DAC Configuration: At its heart,the K15 uses two top-tier ES9039SPRC DAC chips from EsS Technology,arranged in a dual-mono configuration
(one chip per channel). This setupmaximizes channel separation,dynamicrange, and signal purity.
Fully Balanced Design: The entire signa!path, from the DAC output to the headphone amplifiers, is fully balancedThis design minimizes noise and crosstalk, resulting in a cleaner, morepowerful sound.

Specifications

Weight: 200gr
Usage: Indoor & outdoor

Pros and cons

Sustainably produced
Ideal for everyday use
May discolor in direct sunlight

Desktop DAc and Headphone Amplifier

High-end AKM DAC AK4497$*2 | Discrete class-AB transistor current-boosting headphone amplifier circuit
Two ultra-low phase noise femtosecond crystal oscillators(3000mW+3000mW powerful output
DAC and headphone amp · Streaming media · Local playback | Fully balanced audio circuit
3.93-inch touchscreen | infrared remote control included | 2.4G/5G dual-band WlFl + Gigabit Ethernet

Leading the new 'core’generationDual high-end AKM DAC AK4497S

Name: FiiO K15 – Streamer Desktop DAC & Headphone Amplifier with Dual AK4497S
Brand: Fiio
Price: 599.99 USD
Availability: InStock

The K15 is among the first to use two of the newhigh-end AKM DAC chips, AK4479SVQ featuringthe upgraded 'VELVET SOUND'audiotechnology. The chips achieve low distortion, awide dynamic range,andextended signalbandwidth, all at low power consumption. Richdetail is retained in both low and highfrequencies for a natural and immersive sound

VELVETSOUND
VELVET SOUND is a brand that embodies the sound philosophyof AKM’s new-generation audio products. lt aims to achieve'true-to-life sound reproduction'by fully utilizing audiotechnology, delivering an authentic and immersive acousticexperience with no compromises.

<h1>Discrete architecture<br/>Class-AB transistor current-boostingheadphone amplifier circuit</h1>

Discrete architecture
Class-AB transistor current-boostingheadphone amplifier circuit

Within the K15 is a carefully designed discreteheadphone amplifier circuit, featuring an OP +transistor current-boosting design. Acomplementary pair of the classic ONSemiconductor MJE243G/253G delivers highcurrent and low impedance output. This discretecircuit can achieve balanced output power up to3000mw + 3000mw, allowing the K15 toeffortlessly drive both full-sized headphones andin-ear monitors - producing smooth, natural, yetmelodious sound.

Eight operating modes

Fully balanced audio circuit

From DAc decoding, low-pass filtering, gain control, and to headphone amplification, the K15’saudio circuit is a fully differential design. Such a design ensures wide dynamic range while alsoeffectively reducing crosstalk, minimizing noise, and enhancing the quality of audio output.

Physically separated boards

The internal power supply, digital, andanalog sections each lie on separatephysical boards, physically preventingcrosstalk. This effectively ensures theprecision and integrity of processedaudio signals, for pure and qualitysound.

Precisely designed power supply

DC/AC dual power supply
The K15 features a built-in next-generation 30W (12V-2.5A) low-noise, high-efficiency, long-lasting, industrialand instrumentation-grade power supply. The K15 alsosupports external Dc power supplies*, allowing it towork with higher-performance linear power suppliesfor even higher sound quality.
*12V-2.5A external DC power supplies are supported
85~305VAC ultra-wide input voltage range-40°C~85°COperatingtemperature
500000 hours ultra-high reliability

<p><strong>Separate digital and analogsection power supplies</strong><br/>Such a design helps to effectively avoidcrosstalk between the digital and analogsections of the audio circuits by ensuringbetter power isolation and improvedanti-interference abilities.</p>

Separate digital and analogsection power supplies
Such a design helps to effectively avoidcrosstalk between the digital and analogsections of the audio circuits by ensuringbetter power isolation and improvedanti-interference abilities.

Multi-stage analogpower supply
The analog sectionfeaturesprecisely-segmentedmulti-stagepower supply, including stages fordigital-to-analogconversion, LPFand transistors. The power supplyutilizes up to 14 low-dropout linear

Precisely restored signals Every last detail heard

2 Accusilicon low phase noise femtosecond audio crystal oscillators
Inside the K15 is the industry+eading AccuSlllcoN ultra-low phase noise As318-L crystal oscillator(45.1584MHz, 49.1520MHz) that effectively reduces phase noise interference in audio signals. Thisensures precise reproduction of audio signals at various sampling rates, for purer and more stable sound.

High-end parts,All for sound

8 ruby film capacitors+ 32 wafer resistors
Low temperature drift, low noise, mean stablesound quality in both hot and cold environments.
2 Nichicon 3300uF audio capacitors + 4 ELNA MILIC IHigher quality sound with a better soundstage.
Icapacitors+ 8 ELNA RA3 audio capacitors

<h1>Dual master cores Stable and<br/>smooth experience</h1>

Dual master cores Stable and
smooth experience

High-performance multi-core processor X2000: Thisprocessor is powered by a unique design featuringdual XBurst@2 cores + XBurst@0 micro-core, to deliverexceptional computing performance at ultra-lowpower consumption. This ensures precise audio signalprocessing, guaranteeing stable and smooth musicplayback.
Efficient MCU ESP32-s3: Integrated into this chip isa high-performance Xtensa 32-bit Lx7 dual-core
processor and an ultra-low-power coprocessorfeaturing a clock speed of up to 240MHz. This chipenables precise system control for a highly efficientand fast user experience.

A harmonious fusion of squareand round Brilliance in design

The K15 features Fllo's signature design blending square andround elements, merging retro elegance with cutting-edgetechnology. Thoughtfully crafted for both functionality andaesthetics,it features convenient screen controls and multipleknobs for smoother operation. In addition, the grid structureenhances heat dissipation -all showcasing the brilliance of itsmeticulous design.

10-band high-precision PEQ Unlimited fun

All digital inputs of the K15 support PEQ adjustment*. Precisely fine-tune the sound to your liking by simulating andmodifying the frequency response curve of headphones, thanks to Fll0’s proprietary adjustment algorithm and interface.

Multiple protection systems
Listen worry-free

Not only has the device gone through rigorous testing in Fllolabs, it also contains various protection systems that canintelligently detect abnormal conditions and take actionsaccordingly to protect you, avoiding damage to the machine.

Wired or wireless
Always a stable connection

The Gigabit Ethernet port supports fast and stable wired data
transmissions, while the AP6256 Wi-Fi module supports 2.4G and
5G band wireless networks as another way to stably transmitlossless audio.

Wide variety of usage scenarios

Buttons and ports labeled

*Adjusting the equalizer via the webpage requires connecting
tothe Rs232 porton the rear panel.*The maximum output current of the UsB-A
port is 500mA, which is suitable forconnecting to a UsB flash disk. lfyou need
to connect to a mobile hard diskdrive, please use an extra power supply to power it!

FAQ

1.User manual, Quick start guide, DAc driver download link of K15

1. User manual, Quick start guide, DAC driver download link of K15

User manual/Quick start guide download link

https://forum.fiio.com/note/showNoteContent.do?id=202105201631166296804&tid=17

FiiO USB DAC driver download

https://forum.fiio.com/note/showNoteContent.do?id=202105191527366657910&tid=17

FiiO Control App download

Android version:https://forum.fiio.com/note/showNoteContent.do?id=202105071628040377809&tid=17

iOS version: You could search and download 'FiiO Control' from the APP store.

2. What should l do if the K15 is abnormal?

[No sound, noisy sound, no power on]

The following methods can help you troubleshoot the cause:

1.Unplug and replug the power cord; Turn the back switch off, and then turn it on again to reboot the K15;Check whether the voltage switch at the bottom matches the local voltage and whether the fuse is blown.

2.Check whether the usage mode, input and connection are correct.

3.Replace the input terminal: Switch to other input ports, or change to a mobile phone or computer under USB to locate whether the fault is from the K15 or the front end.

4.Replace the output terminal: such as earphones, earphone cables, replace them with other outputs such as line output, balanced output, etc. to locate the fault.

When connecting to the front panel headphone ports, the output selection needs to be switched to [PO] or [PO+PRE]. When connecting to the rear panel output ports, the output selection needs to be switched to [PRE] or [LO] or [PO+PRE].

5.Software side: There are many reasons for the software side failure, which can be eliminated by the following methods, whether the DAC driver is installed, whether the playback software and the output of the system are correspondingly switched to K15, and whether other sampling rate Flac and DSD tracks can be played

*If the methods provided above cannot solve the problem, please contact support@fiio.com with the receipt attached.

[How to provide log files]

When the K15 has some abnormalities, you could provide the abnormal log files to our engineers to analyze.

1.Insert a USB flash disk with more than 10M capacity;

2.Go to 'Menu'-'Other settings', then select'Factory debugging' option. The "Log saving is complete" window will pop up automatically. The log files will be automatically saved to the USB flash

disk.

3.Please send the log files to FiiO customer service.

[No sound after upgrade]

After all upgrades are complete, please turn the AC power switch in rear panel off and on once to let the entire K15 system to power up and reboot.

[Water entry]

Turn it off immediately and stop using it. Do not supply power. Keep it in a dry place. Contact our customer service for help.

3.K15 accessory list, power supplyinstructions

Packing list

K15*1, AC power cord*1, USB data cable*2, Headphone plug adapter*1, Remote control*1, Fuse*1, XLR4 decorative plug*1, Battery*2 (only for China, English, Japan regions), Quick start guide*1, Warranty card*1

[K15 Power Supply Specifications] The K15 utilizes a switching mode power supply with a universal AC line standard interface (unlike the K17, the K15 does not have voltage level selection)

[Fuse Parameters]

250V/500mAH 5.2x20mm

[Function of the grounding post in the rear panel]

1.When K15 is paired with other device which cannot be connected to the power ground, it can be connected through the grounding post.

2.You can connect the metal shell of K15 directly to the earth through the grounding post, which can enhance the anti-static capability of the equipment.

3.Improve the ground loop, potentially to improve loop interference.

[Remote control instructions]

Difference between powering off via panel knob and entering standby mode via remote control

1.When powering off via the panel knob, there will be boot animation after restart.

2.When entering standby mode via remote control standby, no boot animation when you turn it on again and you can wake up the K15 immediately.

4.Instruction of the K15 display, knobs, and menu setting

[Display]

Working mode:

left slide at any position, switch to working mode interface; right slide at any position of working mode interface to exit working mode interface.

Menu interface:

right slide at any position to switch to menu settings interface;left slide at any position in the menu settings interface to exit the menu interface.

In menu setting interface, click the back icon to return to the previous page, click the main interface icon to return to the main interface.

Main interface style:

slide up and down to switch between different main interface styles, VU meter is only valid for local playback and streaming mode.

[Menu knob with button]

Rotate to switch the working mode, short press can take effect immediately, or wait for 2 seconds to take effect automatically.

[Volume knob with button]

Rotate to adjust the volume: turn clockwise to adjust the volume up, counterclockwise to adjust the volume down; Short press to control the screen on/off.

After rotating the volume knob, the display will pop up the volume adjustment interface, you can also adjust to the desired volume by dragging the volume bar on the interface.

[Power on/off selector switch]

Switch the K15on/off, turning counterclockwise to the OFF position to power the K15off; turning clockwise to the ON position power K15on.

[Analog output selector switch]

LO: Output is switched to the rear panel, the volume knob can not adjust the volume. At this time the front panel headphone ports have no output.

PRE: Output is switched to the rear panel, the volume knob can adjust the volume. At this time the front panel headphone port have no output.

PO:Output is switched to the front panel, the volume knob can adjust the volume.At this time the rear panel interface have no output.Please switch to the [PO] when connecting headphones to K15.

PO+PRE : Both the front and rear panels have outputs at the same time, and the volume knob can adjust the volume.

[Gain selector switch]

Five types of gain can be set: Low, Medium, High, Super High and Ultra High.

1.Gain switch: Ultra High,Super High,High, Medium and Low corresponding to the gain of 15dB/12dB/0dB/-3dB/-9dB.

2.Gain is invalid under PRE or LO output.

3.When using gain L/M/H, the internal hardware circuit amplification is low, the headphone output noise floor is lower, suitable for high sensitivity headphones; When using gain SH or UH, the hardware circuit amplification is higher, suitable for high-resistance or over-ear headphones

[Menu Setting Instructions]

Playback settings

1.Set play mode: you can choose sequential, loop play, shuffle play, single play, single loop modes.

2.Set resume mode: you can select resume last position, resume last song and turn off resume mode.

Equalizer

Bypass, Jazz, Rock, R&B, Hip-Hop, Pop, Dance, Classical,Retro,De-essing1,De-essing2, and 10 customized equalizers for a total of 21 equalizer effects.

Filters

K15 has original 6 filters of the DAC chip. You could choose the filter according to your listening preferences.

Here are some introductions to some filters, for reference only. These are only for reference since actual listening also has something to do with the matched device.

Sharp Roll-Off Filter: full and rich sounds, positioned at the very rear. It is suitable for pop music.

Short Delay Sharp Roll-Off Filter: robust, thick and atmospheric sounds, positioned at the rear. With accurate sound positioning and enough sound thickness, it is suitable for pop music.

Low Dispersion Short Delay Filter: neutral sounds, positioned near the middle. It is a traditional filter that can match different music styles. If you have no idea about the filter, you can choose this one.

Slow Roll-Off Filter: coherent and clear sounds, positioned near the middle. It is suitable for classical music.

Short Delay Slow Roll-Off Filter: ultimately untouched sounds, positioned near the front. It can create an immersive music environment with clear and uncontrolled sounds, which is suitable for classical music.

Super Slow Roll-Off Filter: soft sounds, positioned at the very front. It is fast with relatively clean sounds.

Max volume

Self-defined from 20 to 100 levels (can not be customized to volume 0 in order to prevent misuse , leading to users thinking that the machine is malfunctioning.)

Balance

Channel balancing means, by adjusting the output amplitude of the left channel, or the right channel individually, to build a special condition suitable for the user's hearing. For people who have no difference in hearing between left and right ears, there is no need to use this function; the output of the left and right channels of the device is already balanced.

The channel balance value is 0 by default, and the left and right channels can be adjusted by 20 steps each, with a fixed difference of about 0.5dB per step;

Network

Select wired or wireless network

Brightness

You can customize the screen backlight brightness, there are 1-5 levels

Screen time

When the screen is inactive for the set time, the display will turn off automatically. Adjustable 15 seconds to 30 minutes and always on options.

RGB lights

Set menu and volume knob indicator’s status. You can set the constant or breathing state.

Light color:you can set the cycle of gradient. The colors orange, red, blue, cyan blue, purple, yellow, white, green could be selected.

Brightness: 5 levels adjustable.

Theme

Interface style theme selection

Idle time

When K15 is not in working condition (e.g. stop playing) and reaches the set time, the background will turn off part of the circuit power supply to minimize heat generation and save power. When smart idle is enabled,, power consumption can be reduced from 17W to 11W.When resuming the working state (e.g. replaying), K15 automatically enters the working state and resumes output.

Three time values of 2min/10min/20min can be selected. When OFF is selected, it means that the intelligent power saving is not enabled and the K15 will continue to be in the normal working decoding state.

Note:

1.When using line input mode, smart idle function is not supported.

2.When PEQ is enabled, smart idle function is not supported.

U AUDIO

Support UAC1.0 and 2.0 modes. UAC 1.0 is driverless mode: supports PS5, Switch and other drive-free devices;UAC2.0: high bit-rate transmission mode.

Language

Switch between Chinese, English and Japanese

Reset option

You can reset the network, settings, EQ, Bluetooth, media library

Restore all: reset all parameters, will not downgrade firmware version

Others

1.Press the volume knob

You can switch between 'Turn off screen/turn on screen' and 'Mute/Unmute' from'Setting-Ohters-Press the volume knob'.

2.FW update

SOC online upgrade，SOC local upgrade,MCU Upgrade,Update log

3.Factory debug

When the K15 has some abnormalities, you could provide the abnormal log files to our engineers to analyze.

1.Insert a USB flash disk with more than 10M capacity;

2.Go to 'Menu'-'Other settings', then select'Factory debugging' option. The "Log saving is complete" window will pop up automatically. The log files will be automatically saved to the USB flash

disk.

3.Please send the log files to FiiO customer service.

About K15

You can view K15's SOC, MCU, FPGA, IP, SN code and other information Swipe the screen left and right for more information.

The Bluetooth version could be viewed in the FiiO Control APP. XMOS firmware version could be viewed in Window USB DAC driver panel.

5. K15's signal input and output method description

*Note [1]: The volume knob's short press function for screen off/wake-up or mute/unmute will only take effect after being set in the menu.

*Note [2]: If the two USB ports on the front and rear panels are connected, the front one will prevail, and the rear one will be disabled.

*Note [3]: Adjusting the equalizer via the webpage requires connecting to the RS232 port on the rear panel.

*Note [4]: The maximum output current of the USB-A port is 500mA,which is suitable for connecting to a USB flash disk. If you need to connect to a mobile hard disk drive, please use an extra power supply to power it.

[Inputs supported by K15]

K15 supports USB input, coaxial input, optical input, line input, balanced input, Bluetooth input, streaming, local playback, a total of 8 input modes. You can use the remote control or the front panel menu knob to remotely switch the input mode.

[Input Priority]

USB input: Front panel USB input port > Rear panel USB input port

Other input modes can be switched by knob control menu selection, infrared remote control or FiiO Control APP.

Airplay and ROON: The now operating mode will have priority. For example, if you connect ROON to play songs first, and then your phone is connected to airplay. The K15 will switch to airplay mode.

[Output supported by K15]

K15 supports 6.35mm single-ended output, 4.4 balanced output, XLR4 balanced output, RCA line output (LINE OUT), balanced line output (BALANCED OUT) a total of five output modes.

[Output Priority]

[PO] front panel output:4.4mm, 6.35mm and XLR4 balanced output, with the same priority, can be output at the same time. But it is not recommended to use it for a long time at the same time, especially when the impedance of the two earphones is quite different. The output volume may be too loud and can cause the low-impedance headphones in it to overload and cause damage.

[LO] or [PRE] rear panel output:LINEOUT and BALANCE OUT can be output at the same time.

[PO+PRE] the output ports in the front and rear panels have output at the same time; the volume is adjustable.

[Which headphone port on the front panel has the best sound quality?]

Theoretically, the XLR4 balanced port is not much different from the 4.4 balanced port. And the balanced output port sounds more balanced and has more power than the 6.35mm port.

Different headphone ports with different headphones will have a different taste. The sound quality is not good or bad absolute distinction. It is recommended to try and compare by yourself.

[The relevant recommendations for connecting speaker]

1.Generally, when connecting to the amplifier or active speakers, please adjust the volume of the amplifier or active speakers to low level before connecting. Gradually adjust to suitable level after connecting to avoid popping sound.

2.In LO mode, the output volume is max and can not be adjusted . please adjust the volume of the amplifier or active speakers to low level before connecting. Gradually adjust to suitable level after connecting to avoid popping sound.

3.When connecting to speakers with no volume adjustment, it is recommended to use PRE mode in K15.

6. The sample rate supported by K15

USB in: Up to 768kHz/32bit, DSD512 (Native) , MQA 8X

Coaxial in: Up to 192kHz/24bit, DOP64(DOP), MQA not supported

OPT in: Up to 96kHz/24bit

Bluetooth decoding: AAC/SBC/aptX/aptX-LL/aptX-HD/aptX-Adaptive/LDAC

LOCAL PLAY: Up to 384kHz/32bit, DSD256

[Is EQ valid for all modes?]

1.EQ is invalid in line input and balanced input modes.

2.EQ is valid in PRE/LO/PO output modes.

3.When EQ is enabled,the sample rate is supported up to 192kHz.

MQA decoding is only supported in USB DAC mode.

7.K15 indicator light description

The Menu Settings and Volume Settings knobs in K15 adopts RGB indicator light.

[Can the indicator lights of the two knobs be controlled independently to display different states?]

No, these two knob indicators are kept in the same state and designed for synchronized control. So the indicators can only display the same state but not be separated from the independent control display.

[Indicator in the power on/off knob]

It is ordinary RGB so its colour can not adjusted. It will turn off for about 3 seconds when the K15 is powered on and it is a normal phenomenon.

Digital Input Audio Quality Indicators

During digital signal input playback (including USB, optical, coaxial, local playback, and streaming), the indicator color reflects the current audio quality:

Cyan: Sampling rate ≤48 kHz.

Yellow: Sampling rate >48 kHz.

Green: DSD format.

Magenta: MQA format (only supported via USB input with EQ turned OFF).

Bluetooth Format Indicator Colors

For Bluetooth connectivity, the indicator displays specific colors based on the Bluetooth codec:

SBC: Blue

AAC: Cyan

aptX/aptX LL: Purple

aptX-HD: Yellow

aptX Adaptive: Green

LDAC: White

8. How to upgrade the firmware for K15?

[Before upgrading the firmwares for the K15, please note the following]

1. K15 firmwares including: Main controller firmware,MCU firmware, XMOS firmware upgrade and Bluetooth firmware. Please read the corresponding instructions before updating.

2.Except for connecting the K15 to the computer, it is recommended to unplug all other devices or decoders connecting to the USB ports;

3.It is recommended to use USB2.0 data cable. Priority to use the USB cable comes with the K15.

4.During the firmware upgrade process, please do not disconnect the power supply or unplug the USB cable to avoid upgrade failure.

5.After all upgrades are complete, please turn the AC power switch in rear panel off and on once to let the entire K15 system to power up and reboot.

[Main controller firmware upgrade instruction]

OTA update

1.Connect the K15 to the network.

2.Select Main controller Local Upgrade from Settings-Others-FW Update-Main controller(SOC) online upgrade

Solution for K15 OTA upgrade failure: Click here

Local update

Main controller firmware local upgrade video instruction: https://youtu.be/anhViDWo4Ws

1.Download the SOC firmware upgrade package to your computer (the upgrade package has a ".zip" file extension, please do not unzip this file). Copy the upgrade package to the root directory of a USB flash drive.

2.Connect the USB flash drive to the USB A port in the back panel of the K15

3.Select Main controller Local Upgrade from Settings-Others-FW Update-Main controller(SOC) local upgrade and wait for the upgrade to complete. After the upgrade is complete, the system will reboot automatically.

4.After all upgrades are complete, please turn the AC power switch in rear panel off and on once to let the entire K15 system to power up and reboot.

Note:

1.Before upgrading, please make a good backup of the data on the USB flash disk to prevent the data on the USB flash disk from being corrupted due to abnormal power loss.

2.USB flash drive formats supported for upgrade: FAT32/EXFAT/NTFS

3.Please wait for the upgrade process, do not pull out the USB flash drive and do not power off the K15.

4.You could check the main controller firmware version from menu setting-About K15. The firmware has been updated correctly if the latest vesion number is shown.

[Solution for K15 main controller upgrade failure]

Local Upgrade Failure (Unexpected USB Removal/Power Loss)

Recovery Steps:

1.Reconnect power to the K15.

2.Reinsert the USB drive and the device will resume the upgrade automatically .

3.If unsuccessful: Please format the USB drive (FAT32/exFAT recommended) and copy the upgrade package (*.zip file) to the drive. Then reconnect power and reinsert the USB drive to restart the upgrade.

OTA Upgrade Failure (Unexpected Wi-Fi/Ethernet disconnection or power loss) with device freezing in "Updating" screen

Recovery Steps:

1.Ensure the router remains powered (Wi-Fi) or reconnect Ethernet.

2.Power on the K15 and it will reconnects to the same network for OTA upgrade automatically.

3.Upon successful connection, the upgrade resumes from the interruption point.

4.After completion, the device reboots automatically.

If the upgrade fails and keeps stuck in “updating”for more than ten minutes and can't be recovered by restarting or reconnecting to the network, you would need to use a USB flash drive to fix the problem.

Recovery Steps:

1.Download the latest firmware from the official website.

2.Copy the .zip file to a USB drive and unzip it manually. Then rename the unzipped folder to K15_update_images (do not modify file hierarchy).

3.Insert the USB drive into the rear USB-A port and power off the K15 completely.

4.Hold the RESET button and then turn on the AC power switch (keep holding RESET). Release RESET once the black "Updating" screen appears.

5.Wait for about 10 minutes for firmware upgrade completion and the device will auto reboot.

[K15 Network connections instruction]

1.Slide right on the screen to enter the menu settings-network settings.

2.Select wired or wireless network to connect;

3.For WiFi connection, you can enter the WiFi password directly through the touch screen and then confirm it.

Note:

K15 can only remember one WiFi message at this time.

[MCU firmware upgrade instruction]

MCU firmware upgrade video instruction: https://youtu.be/WN-fyWZ53fQ

1.Download the MCU upgrade package to your computer (the upgrade package is a file with suffix ".bin").

2.Connect the RS232 port in K15 to the computer with a USB cable.

3.Select MCU Upgrade from Settings-Others - FW Update-MCU upgrade. There will be a USB flash disk shown in the computer now. Copy the upgrade package to the root directory of the USB flash disk. Then eject the USB flash disk in my computer and the upgrade will start automatically. After the upgrade is completed, the system will reboot automatically.

[XMOS firmware upgrade instruction]

The XMOS firmware could be upgraded on the computer.

1.Connect the [USB IN] port in K15 to the computer with a USB cable.

2.Use the XMOS upgrade tool and firmware files to upgrade.

[Bluetooth firmware upgrade instruction]

After connecting the K15 to mobile phone via Bluetooth, you could upgrade the Bluetooth firmware via the FiiO Control app.

9. How to set the 10 bands PEQ in K15?

EQ is invalid in line input and balanced input modes. All the other input modes(UAC,coaxial,optcial,local playback,streaming) support PEQ function.

[EQ setting in mobile phone end]

1.Install the latest version FiiO Control APP in your mobile phone;

2.Please connect K15 and Mobile phone to the same LAN network

3.Go to FiiO Control APP-Add a new device-Player and you will find FIIO K15 . After successful connection, you will enter the control interface of K15.

4.Tap "Equalizer" to customize audio settings.

[EQ setting in web control end]

1.Connect the K15’s rear RS232 USB port to your computer using a USB cable.

2.Access the PEQ web control link:https://fiiocontrol.fiio.com/ Click "Connect" in the top right corner and select "K15" to establish the connection.

3.Adjust PEQ parameters as needed.

10. How to control K15 in FiiO Control?

To make settings related to the K15 via the FiiO Control APP, please follow this steps:

1.Install the latest version FiiO Control APP in your mobile phone;

2.Please connect K15 and Mobile phone to the same LAN network

Go to FiiO Control APP-Add a new device-Player and you will find FIIO K15 . After successful connection, you will enter the control interface of K15.

Note: The K15's FiiO Control function can be used at any time after powering on the device.

[What to try if the connection fails?]

1.If the K15 device is not found on the APP, please check whether the K15 and the mobile phone are connected to the same LAN and whether the WiFi hotspot of the mobile phone and K15 are the same.

1.You could input the IP address of K15 in FiiO Control to connect. And you can check the current IP address of K15 from settings menu- about K15.Then input the IP address on the APP to connect the K15.

2.You could input the IP address of K15 in FiiO Control to connect. And you can check the current IP address of K15 from settings menu- about K15.Then input the IP address on the APP to connect the K15.

Packing list

1-----------K15*1
2-------Ac power cord*1
3-------Remote control*1
4------XLR4 decorative plug*1
5--------------Fuse*1
6-------------USB data cable*2

7--------Headphone plug adapter*1

8--------Warranty card*1Quick start guide*1

Description

Specifications

Pros and cons

Desktop DAc and Headphone Amplifier

Leading the new 'core’generationDual high-end AKM DAC AK4497S

Discrete architectureClass-AB transistor current-boostingheadphone amplifier circuit

Eight operating modes

Fully balanced audio circuit

Physically separated boards

Precisely designed power supply

Precisely restored signals Every last detail heard

High-end parts,All for sound

Dual master cores Stable andsmooth experience

A harmonious fusion of squareand round Brilliance in design

10-band high-precision PEQ Unlimited fun

Multiple protection systemsListen worry-free

Wired or wireless

Always a stable connection

Wide variety of usage scenarios

Buttons and ports labeled

General Specifications

FAQ

1. User manual, Quick start guide, DAC driver download link of K15

Packing list

Discrete architecture
Class-AB transistor current-boostingheadphone amplifier circuit

Dual master cores Stable and
smooth experience

Multiple protection systems
Listen worry-free