FiiO Desktop DAC and Headphone Amplifier - K15 (B)


* Pictures for reference only.The real product may vary.

Leading the new ‘core’ generation Dual high-end AKM DAC AK4497S
The K15 is among the first to use two of the new high-end AKM DAC chips, AK4479SVQ featuring the upgraded 'VELVET SOUND' audio technology. The chips achieve low distortion, a wide dynamic range, and extended signal bandwidth, all at low power consumption. Rich detail is retained in both low and high frequencies for a natural and immersive sound experience.
VELVET SOUND is a brand that embodies the sound philosophy of AKM’s new-generation audio products. It aims to achieve 'true-to-life sound reproduction' by fully utilizing audio technology, delivering an authentic and immersive acoustic experience with no compromises.
*Trademarks is the property of AKM

Discrete architecture
Class-AB transistor current-boosting headphone amplifier circuit
Within the K15 is a carefully designed discrete headphone amplifier circuit, featuring an OP + transistor current-boosting design. A complementary pair of the classic ON Semiconductor MJE243G/253G delivers high current and low impedance output. This discrete circuit can achieve balanced output power up to 3000mW + 3000mW, allowing the K15 to effortlessly drive both full-sized headphones and in-ear monitors - producing smooth, natural, yet melodious sound.

Eight operating modes
*The max current output of the USB-A port is 500mA, suitable for USB flash drives. If you need to connect a portable hard drive, please connect a separate power supply for it.

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

Physically separated boards
The internal power supply, digital, and analog sections each lie on separate physical boards, physically preventing crosstalk. This effectively ensures the precision and integrity of processed audio signals, for pure and quality sound.

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, industrial and instrumentation-grade power supply. The K15 also supports external DC power supplies*, allowing it to work with higher-performance linear power supplies for even higher sound quality.
*12V-2.5A external DC power supplies are supported
85~305VAC Ultra-wide input voltage range -40°C~85°C O perating temperature
500000 hours Ultra-high reliability

Separate digital and analog
section power supplies
Multi-stage analog power supply
Such a design helps to effectively avoid crosstalk between the digital and analog sections of the audio circuits by ensuring better power isolation and improved anti-interference abilities.
The analog section features a precisely-segmented multi-stage power supply, including stages for digital-to-analog conversion, LPF, and transistors. The power supply utilizes up to 14 low-dropout linear regulators to ensure a continuous supply of stable and pure power.

2 Accusilicon low phase noise femtosecond audio crystal oscillators
Precisely restored signals Every last detail heard
Inside the K15 is the industry-leading ACCUSILICON ultra-low phase noise AS318-L crystal oscillator (45.1584MHz, 49.1520MHz) that effectively reduces phase noise interference in audio signals. This ensures precise reproduction of audio signals at various sampling rates, for purer and more stable sound.

High-end parts,All for sound
2 Nichicon 3300uF audio capacitors + 4 ELNA SILMIC II capacitors + 8 ELNA RA3 audio capacitors
8 ruby film capacitors + 32 wafer resistors
sets of silver-plated oxygen-free copper interconnect wires
High-quality Beryl capacitors
Higher quality sound with a better soundstage.
Low temperature drift, low noise, mean stable sound quality in both hot and cold environments.
The various boards are connected with silver-plated oxygen-free copper wires to ensure high-fidelity signal transmission with minimal loss.
Ultra-low ESR, strong anti-interference abilities, for a stable and pure power supply.

Dual master cores Stable and smooth experience
High-performance multi-core processor X2000: This processor is powered by a unique design featuring dual XBurst@2 cores + XBurst@0 micro-core, to deliver exceptional computing performance at ultra-low power consumption. This ensures precise audio signal processing, guaranteeing stable and smooth music playback.
Efficient MCU ESP32-S3: Integrated into this chip is a high-performance Xtensa 32-bit LX7 dual-core processor and an ultra-low-power coprocessor, featuring a clock speed of up to 240MHz. This chip enables precise system control for a highly efficient and fast user experience.

A harmonious fusion of square
and round Brilliance in design
The K15 features FIIO's signature design blending square and round elements, merging retro elegance with cutting-edge technology. Thoughtfully crafted for both functionality and aesthetics, it features convenient screen controls and multiple knobs for smoother operation. In addition, the grid structure enhances heat dissipation - all showcasing the brilliance of its meticulous design.
Touch control /Knob control /Remote control /FiiO Control App connection

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 and modifying the frequency response curve of headphones, thanks to FIIO’s proprietary adjustment algorithm and interface.
* Digital inputs include USB, coaxial, optical, Bluetooth, streaming media and local playback. *Web PEQ location: Top bar of FIIO website – Support – Web-based PEQ settings

Multiple protection systems
Listen worry-free
Not only has the device gone through rigorous testing in FIIO labs, it also contains various protection systems that can intelligently detect abnormal conditions and take actions accordingly 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 transmit lossless audio.
Independent Ethernet port, supports Gigabit wired network
Supports 2.4G and 5G band wireless networks

Wide variety of usage scenarios

Buttons and ports labeled
*Adjusting the equalizer via the webpage requires connecting to the RS232 port on the rear panel.
*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!

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*1
⑨-----------------------------Quick start guide*1
| General Specifications | |
|---|---|
| Name/Model | K15 |
| Hardware solution | Main control: X2000; MCU: ESP32-S3; DAC: AK4497S*2; USB decoding: XU316; Bluetooth decoding: QCC5125; AMP: MJE243G/253G discrete transistor current amplification |
| Working mode | USB DAC mode/Coaxial decoding mode/Optical decoding mode/Line in mode/Balanced in mode/Bluetooth receiving mode/Streaming media receiving mode/Local playback mode |
| Color | Black/Silver |
| Weight | About 2100g |
| Dimensions | About 244.6x213x66.8mm |
| Volume control | Knob/Touch-on-display/Remote control |
| MQA | Supports MQA full decoding |
| Driver-free mode (Switch mode) | Supported |
| Gain | Ultra high gain mode/Super high gain mode/High gain/Medium gain/Low gain |
| Bluetooth receiving (5.1) | SBC/AAC/aptX/aptX LL/aptX HD/aptX Adaptive/LDAC |
| Display | 3.93-inch LCD (240*1020) bezel-less screen |
| Touch-on-display | Supported |
| PEQ | Supports 10-band PEQ (No PEQ processing in line input and balanced input) |
| FIIO Link | Supports settings through the app |
| WiFi | Supports 2.4G/5G dual-band WiFi |
| Firmware upgrade | SOC firmware: Upgrade through the rear USB-A port MCU firmware: Upgrade through the rear RS232 port XMOS firmware: Upgrade through the front or rear USB-C port |
| Remote control | Supports IR remote control (only the one included in the accessory) |
| Knob indicator light | Supports customizing color, brightness, supports always-on indication or RGB pulsing |
| Screen status indication | Working mode, output mode |
| Max. supported sampling rate (PEQ=OFF) | USB decoding: Up to 768kHz/32bit; DSD512 (Native), Coaxial input decoding: Up to 192kHz/24bit; DSD64, Optical input decoding: Up to 96kHz/24bit, Streaming decoding: Up to 384kHz/32bit; DSD256 (DOP), Local playback: Up to 384kHz/32bit; DSD256 |
| Adaptive impedance | PO: 8~150Ω |
| General Specifications - Buttons and Ports | |
| Knob | Power on/off knob*1+Analog output level knob*1+Gain level knob*1+Volume knob with button*1+Menu knob with button*1 |
| USB port | Type-C USB*3 (Data transmission port*2+RS232 DSP regulating port*1) USB-A*1 (Data transmission port) |
| Balanced headphone out | Standard 4.4mm port*1+XLR4 balanced port*1 |
| Headphone out | Standard 3.5mm port |
| Digital optical input port | Optical port |
| Digital coaxial input port | RCA port |
| Balanced line output port | XLR3 balanced port |
| Single-ended line output port | RCA port |
| Balanced line input port | Standard 4.4mm port |
| Single-ended line input port | RCA port |
| Slide switch | Power switch |
| Housing grounding terminal | M4 banana port (Can be directly connected to use) |
| Ethernet port | 1000Mbps |
| General Specifications - Power Supply Parameters | |
| Power supply | AC 100-240V~50/60Hz; DC 12V/≥2.5A (either-or) |
| Battery capacity | N/A |
| General Specifications - Performance and parameters of headphone output (6.35mm out, USB DAC/Coaxial decoding/Optical decoding, Ultra high gain mode) | |
| Output power 1 | L+R≥1400mW+1400mW (16Ω, THD+N<1%) |
| Output impedance | <1Ω (32Ω) |
| Output power 2 | L+R≥1400mW+1400mW (32Ω, THD+N<1%) |
| Crosstalk | ≥76dB (1kHz@32Ω) |
| Output power 3 | L+R≥180mW+180mW (300Ω , THD+N<1%) |
| THD+N | <0.00054% (1kHz/-12dB@32Ω) |
| Output power 4 | <5.3μV (A-weighted) |
| SNR | ≥122dB (A-weighted) |
| Frequency response | 20Hz~20kHz: attenuation<0.2dB 20Hz~80kHz: attenuation<2.8dB |
| Peak output voltage | >20.6Vp-p |
| General Specifications - Performance and parameters of headphone output (6.35mm out, USB DAC/Coaxial decoding/Optical decoding, Super high gain mode) | |
| Output power 1 | L+R≥1400mW+1400mW (16Ω, THD+N<1%) |
| Output impedance | <1Ω (32Ω) |
| Output power 2 | L+R≥760mW+760mW (32Ω, THD+N<1%) |
| Crosstalk | ≥76dB (1kHz@32Ω) |
| Output power 3 | L+R≥90mW+90mW (300Ω , THD+N<1%) |
| THD+N | <0.00058% (1kHz/-10dB@32Ω) |
| Output power 4 | <5.3μV (A-weighted) |
| SNR | ≥119dB (A-weighted) |
| Frequency response | 20Hz~20kHz: attenuation<0.2dB 20Hz~80kHz: attenuation<2.8dB |
| Peak output voltage | >14.6Vp-p |
| General Specifications - Performance and parameters of single-ended line output (RCA out, USB DAC/Coaxial decoding/Optical decoding) | |
| THD+N | <0.00071% (1kHz/-11dB@10kΩ) |
| SNR | ≥119dB (A-weighted) |
| Crosstalk | ≥119dB (1kHz@10kΩ) |
| Output power 4 | <2.6μV (A-weighted) |
| Frequency response | 20Hz~20kHz: attenuation<0.2dB 20Hz~80kHz: attenuation<2.8dB |
| Line output level | 2.4Vrms (1kHz@10kΩ) |
| General Specifications - Performance and parameters of balanced headphone output (4.4mm/XLR4 out, USB DAC/Coaxial decoding/Optical decoding, Ultra high gain mode) | |
| Output power 1 | L+R≥1400mW+1400mW (16Ω, THD+N<1%) |
| Output impedance | <1.5Ω (32Ω) |
| Output power 2 | L+R≥3000mW+3000mW (32Ω, THD+N<1%) |
| Crosstalk | ≥116dB (1kHz@32Ω) |
| Output power 3 | L+R≥700mW+700mW (300Ω , THD+N<1%) |
| THD+N | <0.00059% (1kHz/-13dB@32Ω) |
| Output power 4 | <9.5μV (A-weighted) |
| SNR | ≥120dB (A-weighted) |
| Frequency response | 20Hz~20kHz: attenuation<0.2dB 20Hz~80kHz: attenuation<2.8dB |
| Peak output voltage | >41Vp-p |
| General Specifications - Performance and parameters of balanced headphone output (4.4mm/XLR4 out, USB DAC/Coaxial decoding/Optical decoding, Super high gain mode) | |
| Output power 1 | L+R≥1400mW+1400mW (16Ω, THD+N<1%) |
| Output impedance | <1.5Ω (32Ω) |
| Output power 2 | L+R≥2800mW+2800mW (32Ω, THD+N<1%) |
| Crosstalk | ≥116dB (1kHz@32Ω) |
| Output power 3 | L+R≥350mW+350mW (300Ω , THD+N<1%) |
| THD+N | <0.00054% (1kHz/-9dB@32Ω) |
| Output power 4 | <9.5μV (A-weighted) |
| SNR | ≥120dB (A-weighted) |
| Frequency response | 20Hz~20kHz: attenuation<0.2dB 20Hz~80kHz: attenuation<2.8dB |
| Peak output voltage | >29Vp-p |
| General Specifications - Performance and parameters of balanced line output (XLR3, USB DAC/Coaxial decoding/Optical decoding) | |
| THD+N | <0.00055% (1kHz/-8dB@10kΩ) |
| SNR | ≥120dB (A-weighted) |
| Crosstalk | ≥117dB (1kHz@10kΩ) |
| Output power 4 | <3.3μV (A-weighted) |
| Frequency response | 20Hz~20kHz: attenuation<0.2dB 20Hz~80kHz: attenuation<2.8dB |
| Line output level | 4.8Vrms (1kHz@10kΩ) |

