FiiO K15 black

The FiiO K15 sets a new milestone in accessible desktop audio. This all-in-one DAC-amplifier integrates the brand-new AKM AK4497S chips from the VELVET SOUND series in a dual-mono configuration, a market first. With its discrete Class AB amplification capable of delivering 3000 mW per channel, network streaming functions (Roon Ready, AirPlay 2), and a design that blends vintage aesthetics with contemporary technologies, the K15 concentrates in a compact chassis what previously required several separate devices.

Dual AKM chips for a new conversion standard

The K15’s digital heart relies on two AKM AK4497S converters, the first commercial application of these chips recently launched by Japanese manufacturer Asahi Kasei Microdevices. These 32-bit DACs embody AKM’s new VELVET SOUND philosophy: faithful reproduction of the source, without coloration or artifice. Their signal-to-noise ratio exceeds 130 dB while total harmonic distortion combined with noise remains below 0.0003%. These chips inherit the DWA (Data Weighted Averaging) technology developed for the flagship AK4499EX model.

The dual-mono configuration implementation allows physical separation of left and right channel processing from the conversion stage, reducing crosstalk and improving spatiality. The K15 natively decodes PCM streams up to 768 kHz in 32 bits and DSD files up to DSD512. Two Accusilicon AS318-L femtosecond oscillators with ultra-low phase noise (45.1584 MHz and 49.152 MHz) ensure precise synchronization and jitter reduction.

Discrete amplification designed for all headphones

The Class AB amplification stage combines operational amplifiers and ON Semiconductor MJE243G/253G power transistors in complementary pairs. This design offers high output current and low impedance, two critical characteristics for driving today’s diverse range of headphones.

In balanced output, the K15 delivers up to 3000 mW per channel at 32 ohms. This power reserve allows it to drive both power-hungry planar headphones and high-impedance models. Conversely, its low output impedance and virtually imperceptible noise floor suit sensitive in-ear monitors without parasitic hiss.

Gain adjustment is performed across five levels. The front panel switch toggles between three modes: headphone output (phones OUT), variable preamp output (pre OUT), or fixed line-level output (line OUT). This flexibility transforms the K15 into a true audio hub capable of directly driving active speakers or integrating into a traditional hi-fi system. The three headphone outputs (6.35 mm single-ended jack, 4.4 mm balanced jack, 4-pin XLR) allow simultaneous connection of multiple headphones.

The audio architecture adopts a fully balanced and differential signal path, from conversion to outputs, improving channel separation and minimizing noise.

A three-board design to isolate each function

The internal structure stands out with its physical separation into three distinct boards: one for the digital section, one for the analog section, and a third for power supply. This arrangement drastically limits electromagnetic interference. The boards communicate via silver-plated oxygen-free copper cables that preserve signal integrity.

The precision-machined aluminum chassis contributes to shielding and heat dissipation. The internal grid structure promotes air circulation to maintain stable temperature during extended sessions.

The power supply incorporates a 30 W switching power supply (12 V – 2.5 A), designed to reduce noise and maximize efficiency. The K15 also accepts an external linear power supply via its dedicated DC input. FiiO has segmented the power supply into several independent stages with fourteen low-dropout linear regulators. Capacitors from reputable brands (Nichicon, ELNA MILIC II and RA3) complete this arrangement.

A retro-modern design that doesn’t hide its ambitions

The K15 adopts the aesthetics of the K17, FiiO’s flagship model praised for its successful marriage of vintage codes and modernity. The chassis blends square and rounded forms reminiscent of 1980s studio equipment. The brushed and anodized aluminum provides a pleasant tactile sensation and premium appearance.

The front panel consists of a 3.93-inch color LCD touchscreen surrounded by two detented knobs with peripheral LED lighting. The physical switches have crisp haptic feedback, inspired by vintage mixing consoles. The three headphone outputs are aligned horizontally below the screen for direct access.

The graphical interface maintains the retro spirit with an animated VU meter reminiscent of tape recorders. The screen displays the current audio format, volume, selected source, and active settings. Touch navigation responds fluidly. An infrared remote control accompanies the device to control main functions remotely. The FiiO Control app (Android, iOS) offers complete control from a smartphone, including access to the 10-band parametric equalizer.

Versatility as a design principle

The K15 fulfills multiple roles simultaneously. As a USB DAC, it connects to computers and decodes high-resolution streams via the XMOS XU316 controller. Digital inputs (coaxial, optical) allow connection of a CD player or any S/PDIF source. The Bluetooth 5.1 input supports aptX, aptX HD, aptX Adaptive, and LDAC codecs for wireless sources.

On the network side, the device integrates dual-band WiFi and a Gigabit Ethernet port. It supports Roon Ready and Apple AirPlay 2. The front-panel USB-A port directly reads files stored on a USB drive (formats up to 384 kHz in PCM and DSD256).

The 10-band parametric equalizer, accessible via the mobile app or dedicated web interface, allows precise adjustment of the response curve. Users can create, save, and share profiles adapted to each headphone. The PEQ works with all digital sources but remains inactive on analog inputs.

A little brother with plenty of character

The K15 positions itself as the affordable alternative to the K17, a model awarded by EISA in 2025. Both devices share the same chassis and ergonomics. Their differences focus on technical aspects: the K17 features AKM AK4499EX chips (flagship model) with AK4191 modulator, a linear power supply with toroidal transformer, and a 31-band equalizer, while the K15 uses the AK4497S, a modern switching power supply, and a 10-band equalizer. Maximum power drops from 4000 mW to 3000 mW per channel.

These adjustments allow FiiO to offer the K15 at approximately half the price, while preserving the essence of its qualities. User feedback emphasizes that both models present very similar tonal signatures, with audible differences only on the most revealing headphones.

Technical Specifications

Digital-to-Analog Conversion

• Digital-to-analog converter: dual AKM AK4497S with VELVET SOUND technology
• Audio clocks: 2 Accusilicon AS318-L oscillators with ultra-low phase noise
  • Frequencies: 45.1584 MHz, 49.152 MHz
• Digital processing: dual-core X2000 architecture with ESP32-S3 microcontroller
• Audio resolution: up to 32-bit / 768 kHz, native DSD512
• Dynamic range: > 130 dB
• Total harmonic distortion + noise (THD+N): < 0.0003%

Headphone Amplification

• Type: discrete Class AB circuit with operational amplifiers and MJE243G / MJE253G transistors (ON Semiconductor)
• Output power: up to 3000 mW + 3000 mW in balanced mode at 32 Ω
• Architecture: fully balanced from conversion to output
• Compatibility: high-impedance headphones, in-ear monitors, studio monitors
• Settings: 8 operating modes with multiple gain levels

Power Supply

• Type: dual internal / external DC-AC power supply
• Internal power supply: 30 W (12 V – 2.5 A) low-noise, high-efficiency
• Mains input: 85 ~ 305 V AC, 50 / 60 Hz
• External power supply compatibility: 12 V – 2.5 A linear power supply
• Advanced design:
  • Multi-stage segmented power supply for DAC, low-pass filters and transistors
  • 14 low-dropout linear regulators
  • High-quality Nichicon, ELNA MILIC II and RA3 capacitors
  • Internal wiring in silver-plated oxygen-free copper

Connectivity

• Digital inputs:
  • USB-B, USB-C (asynchronous)
  • Optical, coaxial
  • Bluetooth
  • Gigabit Ethernet
  • Network playback and local playback
• Audio outputs:
  • Balanced XLR
  • Unbalanced RCA
• Headphone outputs: 4-pin XLR, 4.4 mm, 6.35 mm
• USB-A port: maximum 500 mA power supply for USB flash drive
• Network: 2.4 GHz and 5 GHz Wi-Fi, Gigabit Ethernet

Features and Control

• User interface: touchscreen with dual knob and remote control
• Mobile app: compatible with FiiO Control App
• Equalizer: 10-band parametric equalizer adjustable via FiiO web interface
• Smart protections: overheat and overvoltage protection systems
• Quality control: testing in FiiO laboratory

Design and Construction

• Style: combination of square and rounded shapes with retro-tech aesthetic
• Chassis: high-precision machined aluminum
• Internal structure: separate boards for power supply, analog section and digital section with physical isolation to eliminate interference and crosstalk
• Thermal management: internal grid structure to optimize heat dissipation

Package Contents

• FiiO K15
• Mains power cord
• Remote control
• 4-pin XLR decorative cap
• Spare fuse
• 2 USB cables
• Headphone jack adapter
• Warranty card
• Quick start guide

Dimensions and Weight

• Dimensions (W × H × D): 220 × 60 × 180 mm (approx.)
• Weight: approx. 2.5 kg