FiiO K15

Product information "FiiO K15"
Desktop DAC AMP headphone amplifier with two AK4497S 

  • Two AK4497S VELVET SOUND DAC chips 
  • Discrete Class AB transistor amplifier with 3000 mW + 3000 mW output power 
  • Fully symmetrical audio circuit from input to output 
  • Supports USB DAC (768 kHz/32-bit), DSD512, and full MQA decoding 
  • Bluetooth decoding with LDAC/AAC/SBC 
  • 10-band PEQ equalizer support for all digital inputs 
  • Dual master clock, Accusilicon crystal oscillator with extremely low phase noise 
  • Multi-core X2000 processor and ESP32-S3 MCU for a fast and smooth user experience 
  • Supports playback from USB storage devices, Roon Ready, AirPlay streaming 
  • Supports Wi-Fi 2.4/5 GHz Wi-Fi and Gigabit Ethernet 
  • Advanced thermal design and physical separation of power, digital, and analog boards
  • 3.93-inch touchscreen 
  • Infrared remote control 
  • Hi-Res Audio 

The FiiO K15 is a top-of-the-line desktop DAC and headphone amplifier that combines modern digital decoding and analog precision. 

Leading the new “Core” generation 
Two high-quality AKM DAC AK4497S 
The K15 is one of the first devices to use two of the new high-end AKM DAC chips AK4479SVQ with improved “VELVET SOUND” audio technology. The chips offer low distortion, a wide dynamic range, and extended signal bandwidth with low power consumption. Rich details are preserved in both the low and high frequency ranges, ensuring a natural and impressive sound experience. 
VELVET SOUND is a brand that embodies the sound philosophy of the new generation of AKM audio products. It aims to achieve “realistic sound reproduction” through the full utilization of audio technology and to provide an authentic and impressive sound experience without compromise. 
Discrete architecture 
Class AB transistor current amplifier circuit for headphones The K15 features a carefully developed discrete headphone amplifier circuit with an OP + transistor current amplifier design. A complementary pair of classic ON Semiconductor MJE243G/253G transistors delivers high current and low impedance. This discrete circuit can achieve a balanced output power of up to 3000 mW + 3000 mW, allowing the K15 to effortlessly drive both full-size headphones and in-ear monitors for a smooth, natural, yet melodious sound. 
Eight operating modes 
Streaming media: Enjoy a wide variety of streaming media sources via Roon Ready and AirPlay*. 
Local playback: Supports external USB storage** so you can listen to your private collection. 
Single-ended line input: Receives single-ended analog audio inputs and amplifies them with the K15. 
Balanced line input: Receives balanced analog audio inputs and amplifies them with the K15. USB DAC: XMOS 16-core XU316, supports 768 kHz/32-bit, DSD512, full MQA decoding***. 
Bluetooth decoding: Supports SBC/AAC/LDAC and other codecs. 
Optical decoding: Receives optical signal inputs and functions as an optical decoder. 
Coaxial decoding: Receives optical signal inputs and functions as an optical decoder.
 *Roon Ready certification is pending, please refer to the official announcement from FIIO. 
**The maximum current output of the USB-A port is 500 mA and is suitable for USB flash drives. If you want to connect a portable hard drive, you will need a separate power supply. 
***Full MQA decoding is only available with USB input and EQ=OFF. MQA is not available in bypass mode and with EQ=ON. 
From DAC decoding to low-pass filtering and gain control to headphone amplification, the K15's audio circuitry is completely symmetrical. This design ensures a wide dynamic range while effectively reducing crosstalk, minimizing noise, and improving audio output quality. 
Physically separated circuit boards 
The internal power supply, digital, and analog sections are each located on separate circuit boards, physically preventing crosstalk. This effectively ensures the precision and integrity of the processed audio signals and delivers pure, high-quality sound. 
Precisely engineered power supply 
DC/AC dual power supply 
The K15 features an integrated, low-noise, highly efficient, long-life, next-generation 30 W (12 V-2.5 A) power supply of industrial and instrument quality. The K15 also supports external DC power supplies*, allowing it to be powered by more powerful linear power supplies for even better sound quality. 
*External DC power supplies with 12 V-2.5 A are supported 
Ultra-wide input voltage range (85 to 305 VAC) 
Operating temperature -40°C to 85°C 
500,000 hours of ultra-high reliability 
Separate power supplies for digital and analog sections 
This design helps to effectively prevent crosstalk between the digital and analog sections of the audio circuits by ensuring better power isolation and improved noise rejection capabilities. 
Multi-stage analog power supply 
The analog section features a precisely segmented multi-stage power supply, including stages for digital-to-analog conversion, LPF, and transistors. The power supply uses up to 14 linear regulators with low voltage drop to ensure a continuous supply of stable and pure power. 
Precisely restored signals
Every little detail can be heard 
2 Accusilicon femtosecond audio quartz oscillators with low phase noise 
The K15 features the industry-leading ACCUSILICON quartz oscillator AS318-L (45.1584 MHz, 49.1520 MHz) with extremely low phase noise, which effectively reduces phase noise in audio signals. This ensures precise reproduction of audio signals at various sampling rates and thus a purer and more stable sound. 
High-quality components 
Everything for sound 
2 Nichicon 3300uF audio capacitors + 4 ELNA MILIC II capacitors + 8 ELNA RA3 audio capacitors 
Better sound quality with a better sound stage. 
8 ruby film capacitors + 32 wafer resistors 
Low temperature drift, low noise, consistently stable sound quality in both hot and cold environments. 
High-quality beryllium capacitors 
Ultra-low ESR value, strong interference suppression for a stable and pure power supply.
4 sets of silver-plated, oxygen-free copper interconnect wires 
The various circuit boards are connected with silver-plated, oxygen-free copper wires to ensure high-resolution signal transmission with minimal loss. 
Two master cores
Stable and smooth experience 
High-performance multi-core processor X2000: This processor is based on a unique design with two XBurst@2 cores + XBurst@0 micro-core and offers exceptional computing power with extremely low power consumption. This ensures precise audio signal processing and guarantees stable and smooth music playback. 
Efficient MCU ESP32-S3: This chip integrates a powerful Xtensa 32-bit LX7 dual-core processor and an extremely power-efficient coprocessor with a clock speed of up to 240 MHz. This chip enables precise system control for a highly efficient and fast user experience. 
A harmonious fusion of angular and rounded 
Brilliance in design 
The K15 features FIIO's signature design, which combines angular and rounded elements to blend retro elegance with cutting-edge technology. Carefully designed with both functionality and aesthetics in mind, it features convenient screen controls and multiple rotary knobs for smoother operation. In addition, the grid structure improves heat dissipation – all of which underlines the brilliance of its thoughtful design. 
Touch control 
Button control 
Remote control 
FiiO Control app connection 
10-band high-precision PEQ 
Unlimited fun 
All digital inputs on the K15 support PEQ adjustment*. Thanks to FIIO's proprietary setting algorithm and user interface, you can precisely adjust the sound to your liking by simulating and modifying the frequency response curve of the headphones. 
* Digital inputs include USB, coaxial, optical, Bluetooth, streaming media, and local playback. 
*Web PEQ location: Top bar of the FIIO website – Support – Web-based PEQ settings 
Multiple protection systems 
Worry-free listening 
Not only has the device undergone rigorous testing in FIIO's laboratories, but it also features various protection systems that intelligently detect abnormal conditions and take appropriate measures to protect you and prevent damage to the device. 
Amplifier temperature detection 
Overvoltage protection OVP 
Output overload detection 
DC output protection 
Overcurrent protection for the power supply 
Wired or wireless 
Always a stable connection 
The Gigabit Ethernet port supports fast and stable wired data transfers, while the AP6256Wi-Fi module supports 2.4 and 5 GHz wireless networks as an additional option for stable transmission of lossless audio data. 
Versatile application options 
Scenario 1: USB decoding 
Scenario 2: Streaming media (Roon or Airplay) 
Scenario 3: Local playback 
Scenario 4: Optical/coaxial decoding 
Scenario 5: Single-ended/balanced line input 
Scenario 6: Bluetooth decoding 
Connections and inputs
USB-C input (XMOS xU316) 
Coaxial and optical digital inputs 
Balanced and unbalanced line inputs 
USB-A storage input 
Gigabit Ethernet + dual-band Wi-Fi 

Specifications
DAC chip: Two AKM AK4497S USB decoding: 768 kHz/32-bit, DSD512, full MQA decoding 
Bluetooth: LDAC, AAC, SBC (to be confirmed) 
Output power: 3000 mW + 3000 mW with balanced output 
Clock Accusilicon: AS318-L (45.1584 MHz & 49.1520 MHz) 
PEQ support: 10-band PEQ on all digital inputs 
Streaming: AirPlay, Roon Ready 
Processor: X2000 dual-core + ESP32-S3 MCU 
Power supply: 30 W internal power supply (12 V/2.5 A) + DC input support 
Operating temperature: -40 °C to 85 °C 
Network: Gigabit Ethernet, dual-band Wi-Fi (2.4 GHz and 5 GHz) 

Basic specifications and parameters 
Color: Black/silver 
Dimensions: approx. 244.6 x 213 x 66.8 mm 
Weight: approx. 2100 g 
Hardware configurations 
Master control: X2000, ESP32-S3 
DAC: AK4497S*2 USB: XMOS XU316 
Headphone amplifier transistor: MJE243G/253G 
Display: 3.93-inch LCD 
Bluetooth specifications 
Bluetooth reception: Bluetooth 5.1, SBC/AAC/aptX/aptX LL/aptX HD/atpX Adaptive/LDAC 
Decoding specifications 
USB DAC: 768 kHz/32-bit; DSD512 (native) 
Coaxial input: 192 kHz/24-bit; DSD64 
Optical input: 96 kHz/24-bit 
Local playback: 384 kHz/32-bit; DSD256 
Streaming playback: 384 kHz/32-bit; DSD256 (DOP) 
Headphone outputs 
Output power 1: L+R ≥ 1400 mW + 1400 mW (32 Ω SE, THD+N <1 %, ultra-high gain mode) 
Output power 2: L+R ≥ 3000 mW + 3000 mW (32 Ω BAL, THD+N <1 %, ultra-high gain mode) 
Output power 3: L+R ≥ 180 mW + 180 mW (300 Ω SE, THD+N <1 %, ultra-high gain mode)
Output power 4: L+R ≥ 700 mW + 700 mW (300 Ω BAL, THD+N <1 %, ultra-high gain mode) 
Line outputs 
RCA output: L+R=2.4 Vrms+2.4 Vrms (1 kHz at 10 kΩ) 
XLR output: L+R=4.8 Vrms+4.8 Vrms (1 kHz at 10 kΩ) 
Audio parameters 
Frequency response: 20 Hz to 80 kHz, attenuation < 2.8 dB 
SNR: ≥ 122 dB (A-weighted) 
Noise: < 5.3 μV (A-weighted) 
THD+N: < 0.00054 % (1 kHz/-12 dB at 32 Ω) 

What`s in the box
K15*1 
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, England, and Japan) 
Quick start guide*1 
Warranty card*1
Informationen zum Hersteller
GUANGZHOU FIIO ELECTRONICS TECHNOLOGY CO LTD
No.21, Longliang Road, Xialiang Village,Longgui Street, Baiyun District,
510430 GuangZhou, CHINA
www.fiio.com
support@fiio.com
EU-Verantwortlicher
NT Global Distribution GmbH
Buntentorsdeich 10
28201 Bremen
Deutschland
www.nt-global.de
info@nt-global.com