A fully-balanced streaming DAC/amp

The FiiO K15 is a fully-balanced DAC and headphone amplifier that combines streaming, local playback, and DAC/amp functionality in a single high-performance package. With dual AK4497S DAC chips, a discrete Class-AB headphone amp circuit, PEQ tuning, and a wide range of inputs and outputs—including balanced 4.4mm and XLR4 headphone jacks—the K15 will revive your audio setup. Whether you're playing from Roon, Bluetooth, a CD player, or a USB flash drive, the K15 decodes, amplifies, and delivers it all.

Dual AKM DACs with VELVET SOUND

At the core of the K15 are two AK4497S DAC chips, part of AKM’s newest generation of VELVET SOUND processors. These chips are beloved by audiophiles for their dynamic range, low distortion, and warm, lifelike tonality. 

Discrete Class-AB headphone amplification

The K15’s headphone amplifier circuit uses a discrete OP + transistor current-boosting design based on the ON Semiconductor MJE243G/253G. This Class-AB circuit with carefully matched components and a balanced topology delivers up to 3000mW per channel, driving demanding planar magnetics and high-impedance dynamics with ease, while keeping noise low enough for IEMs.

Eight playback modes

From USB DAC to Bluetooth receiver, from Roon streamer to local file player, adaptability is the K15’s middle name. Plug in your phone via USB-C, connect wirelessly via LDAC or AirPlay, or load up a flash drive with FLACs. Balanced and unbalanced line inputs let you use it as a headphone amp only, while digital coaxial and optical inputs make it easy to integrate legacy gear like CD players. 

Fully-balanced signal path from start to finish

The K15 uses a fully differential circuit from digital-to-analog conversion through to the final headphone output stage. This architecture improves dynamic range, reduces noise, and cuts down on crosstalk, resulting in clean, spacious playback even at high volumes or with complex mixes.

Physically-isolated circuit sections

To keep things quiet, the K15 separates the digital, analog, and power supply boards inside the chassis. By physically distancing these sections, the K15 reduces the risk of signal interference and keeps the sound clear and accurate.

Low-noise power

The built-in 30W power supply is low-noise, industrial-grade, and ready for global voltages from 100V to 240V AC. Want to use your own linear supply? Just plug it into the DC input. Power is also split across multiple rails to isolate digital and analog sections, with up to 14 LDO regulators keeping voltage stable for critical stages like the DAC and amp.

Accusilicon femtosecond clocks

To support ultra-precise digital playback, the K15 uses dual Accusilicon AS318-L femtosecond crystal oscillators (45.1584MHz and 49.1520MHz). These clocks minimize phase noise and jitter, ensuring stable decoding for high-res formats up to DSD512 and 768kHz PCM.

Powerful dual-core architecture

A high-performance dual-core X2000 handles streaming and digital playback duties, while the ESP32-S3 microcontroller manages the system interface, display, and controls. Together, they keep the K15 responsive, reliable, and future-proof with OTA firmware support and app control.

10-band PEQ

With support for FiiO’s 10-band PEQ across all digital sources—including streaming, Bluetooth, USB, and optical—you can sculpt the sound to your taste or compensate for headphone quirks. Adjust settings from the web-based interface and store multiple presets for quick recall.

Product highlights

• Dual AKM AK4497S DAC chips with VELVET SOUND
  
• Discrete Class-AB headphone amplifier with MJE243G/253G transistors
  
• 3000mW+3000mW output (balanced)
  
• Fully balanced circuit topology
  
• Dual Accusilicon femtosecond oscillators
  
• USB DAC, streaming, Bluetooth, coaxial/optical, local playback
  
• 10-band PEQ across all digital inputs
  
• Touchscreen display with remote and knob control
  
• Built-in and external power supply support
  
• Wi-Fi (2.4/5GHz) + Gigabit Ethernet
  
• Roon Ready, MQA full decoding, LDAC
  
• Physically isolated analog, digital, and power boards
  

Specs

• Name/Model: K15

• Hardware solution: X2000
• MCU: ESP32-S3
• DAC: AK4497S*2
• USB decoding: XU316
• Bluetooth decoding: QCC5125
• AMP: MJE243G/253G discrete transistor current amplification

• Working mode: USB DAC / Coaxial / Optical / Line in / Balanced in / Bluetooth / Streaming / Local

• Color: Black/Silver

• Weight: About 2100g

• Dimensions: About 244.6×213×66.8mm

• Volume control: Knob / Touch / Remote

• MQA: Supports full decoding

• Driver-free mode: Supported

• Bluetooth receiving (5.1): SBC / AAC / aptX / aptX LL / aptX HD / aptX Adaptive / LDAC

• Gain: Ultra / Super high / High / Medium / Low

• Display: 3.93-inch LCD (240×1020) bezel-less

• Touch-on-display: Supported

• PEQ: Supports 10-band PEQ (not in line or balanced input)
• 
FiiO Link: App supported

• WiFi: 2.4G/5G dual-band

• Firmware upgrade:
  • SOC via rear USB-A
    
  • MCU via RS232
    
  • XMOS via front/rear USB-C

• Remote control: IR remote (included)

• Knob indicator light: Custom color/brightness/RGB pulse

• Max. supported sampling rate (PEQ = OFF):
  
  • USB: 768kHz/32bit; DSD512
    
  • Coaxial: 192kHz/24bit; DSD64
    
  • Optical: 96kHz/24bit
    
  • Streaming: 384kHz/32bit; DSD256 (DOP)
    
  • Local: 384kHz/32bit; DSD256

• Adaptive impedance: PO: 8150Ω, BAL: 8350Ω
• USB ports:
  • 3× USB-C (2× data, 1× RS232 DSP)
  • 1× USB-A (data)
• Balanced headphone out:
  • 4.4mm
  • XLR4
• Headphone out:
  • 3.5mm
• Digital optical in: Optical port

• Digital coaxial in: RCA

• Balanced line out: XLR3

• Single-ended line out: RCA
• 
Balanced line in: 4.4mm

• Single-ended line in: RCA

• Slide switch: Power

• Grounding terminal: M4 banana port
• 
Ethernet port: 1000Mbps
• Power supply: AC 100–240V~50/60Hz; DC 12V ≥ 2.5A
• Unbalanced headphone out (6.35mm, USB DAC, Ultra high gain):
  • Output 1: 1400mW + 1400mW (16Ω)
  • Output 2: 1400mW + 1400mW (32Ω)
  • Output 3: 180mW + 180mW (300Ω)
  • THD+N: < 0.00054%
  • Crosstalk: ≥76dB
  • SNR: ≥122dB
  • Output impedance: <1Ω
  • Output voltage: >20.6Vp-p
  • Noise: <5.3μV
  • FR: 20Hz–80kHz (<2.8dB)
• Balanced headphone out (4.4mm/XLR4, USB DAC, Ultra high gain):
  • Output 1: 1400mW + 1400mW (16Ω)
  • Output 2: 3000mW + 3000mW (32Ω)
  • Output 3: 700mW + 700mW (300Ω)
  • THD+N: < 0.00059%
  • Crosstalk: ≥116dB
  • SNR: ≥120dB
  • Output voltage: >41Vp-p
  • Output impedance: <1.5Ω
  • Noise: <9.5μV
  • FR: 20Hz–80kHz (<2.8dB)
• Performance and parameters of balanced line output (XLR3, USB DAC / Coaxial decoding / Optical decoding)
  • THD+N: < 0.00055% (1kHz / –8dB @ 10kΩ)
  • Crosstalk: ≥117dB (1kHz @ 10kΩ)
  • Frequency response:
    • 20Hz ~ 20kHz: attenuation < 0.2dB
    • 20Hz ~ 80kHz: attenuation < 2.8dB
  • SNR: ≥120dB (A-weighted)
  • Output power 4: < 3.3μV (A-weighted)
  • Line output level: 4.8Vrms (1kHz @ 10kΩ)

What’s included

• K15 ×1
  
• AC power cord ×1
  
• Remote control ×1
  
• XLR4 decorative plug ×1
  
• Fuse ×1
  
• USB data cables ×2
  
• Headphone plug adapter ×1
  
• Warranty card ×1
  
• Quick start guide ×1