FiiO K15 Dual AK4497S Desktop DAC & Headphone Amplifier

• Two AK4497S VELVET SOUND DAC Chips
• Discrete Class‑AB transistor headphone amplifier with an output power of 3000 mW + 3000 mW
• Fully balanced 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 with ultra‑low‑phase‑noise Accusilicon crystal oscillator
• Multi‑core X2000 processor and ESP32‑S3 MCU for fast, smooth user experience
• Supports USB storage playback, Roon Ready, and AirPlay streaming
• Supports dual‑band Wi‑Fi (2.4 / 5 GHz) and Gigabit Ethernet
• Advanced thermal design and physical separation of power, digital, and analog boards
• 3.93‑inch touchscreen
• Infrared remote control
• High‑resolution audio

The FiiO K15 is a high‑end desktop DAC and headphone amplifier that combines modern digital decoding with analog precision.

Dual High‑Quality AKM AK4497S DAC Chips

The K15 is among the first to utilize two of AKM’s new high‑end AK4497SVQ DAC chips featuring enhanced "VELVET SOUND" audio technology. These deliver low distortion, wide dynamic range, and wide signal bandwidth with low power consumption. They preserve rich detail in both low and high frequencies for a natural, immersive listening experience.

Discrete Class‑AB Transistor Headphone Amplifier

The K15 features a meticulously designed discrete amplifier circuit with an OP+ current‑mode transistor design. A complementary pair of classic ON Semiconductor MJE243G/253G transistors delivers high current and low impedance. This discrete circuit provides up to 3000 mW + 3000 mW symmetrical output, effortlessly driving both full‑size headphones and IEMs for smooth, natural, melodious sound.

Eight Operating Modes

1. Media Streaming — Enjoy a variety of streaming sources via Roon Ready and AirPlay\*.

2. Local Playback — Supports external USB storage\*\*, so you can access your private collection.

3. Single‑Ended Line Input — Accepts and amplifies single‑ended analog audio.

4. Balanced Line Input — Accepts and amplifies balanced analog audio.

5. USB DAC — Powered by XMOS’ 16‑core XU316; supports full decoding at 768 kHz/32‑bit, DSD512, and MQA\*\*\*.

6. Bluetooth Decoding — Supports SBC, AAC, LDAC, and more.

7. Optical Decoding — Receives and decodes optical input.

8. Coaxial Decoding — Receives and decodes coaxial input.

\* Roon Ready certification is pending—see FiiO’s official announcement.

\*\* USB-A port provides up to 500 mA—suitable for flash drives. Portable hard drives require separate power.

\*\*\* Full MQA decoding only via USB input and when EQ is OFF. Not available in Bypass mode or with EQ enabled.

From the DAC decoder to the low‑pass filter, gain control, and headphone amplifier, the K15’s audio circuit is fully symmetrical—ensuring wide dynamic range, reduced crosstalk, minimal noise, and superior output quality.

Physically Separated Boards

The internal power, digital, and analog components each reside on separate boards—physically isolating them to prevent crosstalk. This ensures signal integrity and precision, delivering pure, high‑quality sound.

Dual AC/DC Power Options

The K15 includes an integrated industrial‑grade, low‑noise, highly efficient 30 W (12 V/2.5 A) power supply. It also supports external DC power adapters\* for enhanced audio quality.

\* Supports external DC adapters rated 12 V/2.5 A

Ultra‑Wide Input Voltage Range — AC 85 V to 305 V

Operating Temperature Range — –40 °C to 85 °C

Reliability — Rated for 500,000 hours

Separate Power Supplies — Digital and analog sections each have their own supply, aiding noise suppression and current isolation.

Multi‑Stage Analog Power — Analog section powered by a segmented multistage supply including DAC, LPF, and transistor stages, plus up to 14 low-dropout linear regulators for stable, pure delivery.

Dual Femtosecond‑Crystal Accusilicon Oscillators with Low Phase Noise

Equipped with industry-leading ACCUSILICON AS318‑L oscillators (45.1584 MHz and 49.1520 MHz) to reduce phase noise, ensuring accurate audio sampling and exceptionally pure and stable playback.

Includes:

* 2 × Nichicon 3300μF audio capacitors

* 4 × ELNA MILIC II capacitors

* 8 × ELNA RA3 audio capacitors for rich soundstage

* 8 ruby film capacitors + 32 wafer resistors for low thermal drift and noise in varied temperatures

* High‑quality beryllium capacitors with ultra‑low ESR for noise suppression and stable power delivery

* 4 sets of silver‑plated, oxygen‑free copper wires connecting PCBs—ensuring high‑resolution signal transmission with minimal losses.

Stable and Smooth Experience

* High‑Performance Multi‑Core X2000 Processor — Dual XBurst\@2 cores plus an XBurst\@0 micro‑core—delivering exceptional processing power and ultra‑low energy usage for precise audio signal processing and stable playback.

* Efficient ESP32‑S3 MCU — Dual‑core Xtensa LX7 32‑bit processor with ultra‑low‑power coprocessor up to 240 MHz—enabling rapid, precise system control and a highly responsive user interface.

Function Meets Aesthetic Brilliance

The K15’s exclusive FiiO design blends retro square and round elements, merging elegance with modern tech. Carefully crafted for both functionality and aesthetics, it features smooth on-screen controls and multiple knobs for effortless use. The mesh structure enhances thermal dissipation—highlighting thoughtful, refined design.

Control Methods

Touch screen | Button controls | Remote control | FiiO Control app

### High‑Precision 10‑Band PEQ

Unlimited Customization

All digital inputs support 10‑band PEQ\*. With FiiO’s proprietary tuning algorithm and UI, you can precisely tailor sound to your preference—simulating or customizing headphone frequency response curves.

\* Digital inputs include USB, coaxial, optical, Bluetooth, media streaming, and local playback.

\* PEQ web settings available via: top menu on FIIO’s website – Support – Web‑Based PEQ Settings.

Safe Listening Assured

Beyond extensive lab testing, the K15 incorporates intelligent protection systems to detect and respond to anomalies—protecting you and the unit:

* Amplifier temperature monitoring

* Overvoltage protection (OVP)

* Output overload detection

* DC output protection

* Power input overcurrent protection

### Wired or Wireless — Always Stable

* Gigabit Ethernet – Fast, stable wired audio data transmission

* AP6256 Wi‑Fi Module – Supports dual‑band (2.4 / 5 GHz) wireless, enabling stable lossless audio data transfer

Versatile Use Cases

| Scenario | Description                        |

| -------- | ---------------------------------- |

| 1        | USB decoding                       |

| 2        | Media streaming (Roon or AirPlay)  |

| 3        | Local playback                     |

| 4        | Optical / coaxial decoding         |

| 5        | Single‑ended / balanced line input |

| 6        | Bluetooth decoding                 |

Connections & Inputs

* USB‑C input (XMOS XU316)

* Coaxial & optical digital inputs

* Balanced and single‑ended line inputs

* USB‑A for storage

* Gigabit Ethernet + dual‑band Wi‑Fi

Technical Specifications

* DAC Chips: Dual AKM AK4497S

* USB Decoding: 768 kHz/32‑bit; DSD512; full MQA

* Bluetooth: LDAC, AAC, SBC (to be confirmed)

* Output Power: 3000 mW + 3000 mW (balanced)

* Clock: Accusilicon AS318‑L (45.1584 MHz & 49.1520 MHz)

* PEQ: 10‑band across all digital inputs

* Streaming: AirPlay, Roon Ready

* Processor: X2000 Dual Core + ESP32‑S3 MCU

* Power: Internal 30 W (12 V/2.5 A) + DC input support

* Operating Temp.: –40 °C to 85 °C

* Networking: Gigabit Ethernet; dual‑band Wi‑Fi (2.4 / 5 GHz)

Base Parameters

* Color Options: Black / Silver

* Dimensions: Approx. 244.6 × 213 × 66.8 mm

* Weight: Approx. 2100 g

Hardware Configurations

* Main Controller: X2000 & ESP32‑S3

* DAC: 2 × AK4497S

* USB Interface: XMOS XU316

* Headphone Amp Transistors: MJE243G/253G

* Display: 3.93‑in LCD

Bluetooth Specifications

* Bluetooth Version: 5.1

* Supported Codecs: SBC, AAC, aptX, aptX LL, aptX HD, aptX Adaptive, LDAC

Decoding Capabilities

* 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: 384 kHz/32‑bit; DSD256 (via DoP)

Headphone Outputs

1. SE, 32 Ω, UHG: ≥ 1400 mW + 1400 mW (THD+N < 1%)

2. BAL, 32 Ω, UHG: ≥ 3000 mW + 3000 mW (THD+N < 1%)

3. SE, 300 Ω, UHG: ≥ 180 mW + 180 mW (THD+N < 1%)

4. BAL, 300 Ω, UHG: ≥ 700 mW + 700 mW (THD+N < 1%)

Line Outputs

* RCA: 2.4 Vrms + 2.4 Vrms (1 kHz @ 10 kΩ)

* XLR: 4.8 Vrms + 4.8 Vrms (1 kHz @ 10 kΩ)

Audio Metrics

* Frequency Response: 20 Hz–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 @ 32 Ω)

In the Package

* K15 unit × 1

* Power cable × 1

* USB data cables × 2

* Headphone adapter × 1

* Remote control × 1

* Fuse × 1

* XLR4 decorative cap × 1

* Batteries × 2 (for China, UK, Japan only)

* Quick start guide × 1

* Warranty card × 1