FiiO K17 Desktop DAC and Headphone Amp

The FiiO K17 is a flagship desktop DAC and headphone amplifier, and the winner of EISA’s Best Product award for headphone amplifiers in 2025–2026. FiiO built it as the successor to the K9 Pro and as an exploration of what a high-end desktop DAC/amp can be: a blend of retro elegance and modern technology. Inside are AKM’s flagship AK4191 and two AK4499EX DACs, a fully discrete class AB amplifier with up to 4,000mW per channel, a 64-bit DSP that brings a 31-band lossless PEQ to every input, and a network streamer with AirPlay and Roon Ready. With eight working modes, seven outputs, a 3.93-inch touch screen, five knobs and a remote, it can be the hub of your whole desk system.

Flagship AKM conversion: AK4191 + 2 × AK4499EX

The K17 uses AKM’s flagship chip combination: an AK4191 modulator feeding two AK4499EX DACs, one for each channel. An 8-channel to 4-channel low-pass filter design reduces common-mode interference for better channel separation and dynamics. The architecture fully separates the digital and analogue sections, and FiiO’s newly developed “DWA ROUTING” technology gives an even cleaner background and improved resolution.

From the DAC through I/V conversion and low-pass filtering to the headphone amplifier, the entire audio circuit is fully differential, for high dynamic range and much lower crosstalk. The I/V and filter stages use multiple low-noise, precision OPA1612 op-amps.

A discrete amplifier with 4,000mW per channel

The headphone amplifier is a carefully crafted, fully discrete circuit: an op-amp plus transistor current amplification design, built around the classic pair of ON Semiconductor MJE243/253 transistors working in class AB. It delivers high current with low output impedance, for up to 4,000mW + 4,000mW into 32Ω from the balanced outputs, nearly double the K9 Pro ESS, and 950mW per channel into 300Ω. That lets it drive all kinds of headphones and IEMs easily, with a smooth, pleasant and natural sound. Five gain levels (low, medium, high, super high and ultra high) let you match it to anything from sensitive IEMs to demanding full-size headphones.

To get the best sound, FiiO deliberately sets the output stage’s quiescent current relatively high. Together with the linear power supply and the flagship DACs, this means the K17 runs warmer than most desktop units. That is normal: the four-sided heat-sink design spreads the heat, and temperature protection is built in.

A 64-bit DSP and a 31-band lossless PEQ

An M21586Q DSP chip performs double-precision 64-bit floating-point calculations at 360MHz. With a high-performance ES9821Q ADC and a custom ultra-low phase noise femtosecond oscillator, it lets you use a 31-band high-precision lossless PEQ in every input mode, analogue inputs included, keeping the signal high-fidelity after processing. The same chip provides robust output protection for your headphones and other connected equipment.

FiiO’s DEL (Dual Engine Limiter) technology and its own algorithms add dynamic range compression and expansion (DRC/DRE), limiter and compressor controls. PCM from 44.1kHz to 96kHz is processed without sample-rate conversion, and each band offers gain from +12 to −24dB and a Q from 0.4 to 128, so you can correct your headphones’ frequency response or simulate another’s. Settings can be exported, imported, shared and saved. Adjust the PEQ on the touch screen, in the FiiO Control app or, with the K17 connected to a Windows or Mac computer, in FiiO’s web PEQ tool in Chrome, Edge or Opera. It applies to the headphone, line and pre-outputs, but not to the coaxial and optical outputs.

Eight working modes

• USB DAC: an XMOS XU316 plays PCM up to 768kHz/32-bit, native DSD512 and fully decoded MQA from a computer or phone, through the front or rear USB-C port (the front takes priority). It draws no power from your phone. Macs need no driver; Windows uses FiiO’s free USB DAC driver, and a driver-free mode (FiiO calls it Switch mode) is available too.
• Coaxial and optical: up to 192kHz/24-bit and DSD64 over coaxial, and 96kHz/24-bit over optical.
• Line in and balanced in: RCA and 4.4mm analogue inputs, amplified by the K17 and processed by the PEQ.
• Bluetooth: a Qualcomm QCC5125 Bluetooth 5.1 receiver with LDAC, aptX Adaptive, aptX HD, aptX LL, aptX, AAC and SBC, for music (not calls).
• Streaming: AirPlay, Roon Ready and QPlay over gigabit Ethernet or dual-band 2.4/5GHz Wi-Fi (AP6256), up to 384kHz/32-bit and DSD256, plus NAS playback over NFS and SMB with one-tap access from the FiiO Control app. QPlay and NAS playback need K17 firmware V265 and FiiO Control V4.5.0 or later.
• Local playback: plug a USB flash drive into the rear USB-A port and play files up to 384kHz/32-bit and DSD256, browsing six tracks per screen.

Seven outputs for headphones, speakers and more

On the front are 6.35mm single-ended, 4.4mm balanced and 4-pin XLR balanced headphone outputs; on the back, an RCA line output (2.5Vrms), an XLR balanced line output (5Vrms), and coaxial (up to 192kHz/24-bit, DSD64) and optical (192kHz/24-bit) outputs. The output knob chooses PO for headphones, PRE for a volume-controlled feed to active speakers or a power amplifier, LO for a fixed full-level feed to an amplifier with its own volume control, or PO+PRE for headphones and speakers together. The three headphone sockets work at the same time, but FiiO advises against using two pairs for long, especially if their impedances are very different. The coaxial and optical outputs are always on, at a fixed level, and are silent in the analogue input modes.

Separate boards and a 35W linear power supply

The power supply, digital and analogue sections sit on physically separate circuit boards to avoid interference between them, for purer, cleaner sound. Silver-plated oxygen-free copper cables (four sets) carry the audio between boards with minimal loss.

A custom high-quality, low-noise transformer powers a 35W linear supply, and five large 4,700µF electrolytic capacitors keep ample power in reserve. The digital and analogue circuits have separate supplies, and the analogue circuit has a multi-stage supply with dedicated regulation for the DAC, low-pass filter and transistor stages; low-noise, high-PSRR TPS7A47 and TPS7A33 LDO regulators then provide stable, clean power.

Three femtosecond clocks

Three industry-leading ACCUSILICON ultra-low phase noise femtosecond oscillators (AS318-L at 45.1584MHz and 49.1520MHz, and AS318-Pro at 24.576MHz) greatly reduce the effect of phase noise, so every sample rate is restored precisely and faithfully for a purer, more consistent sound.

High-end parts throughout

Eight Panasonic film capacitors and 32 wafer resistors keep noise and temperature drift low, so the sound stays consistent whether the room is hot or cold. Beryl solid capacitors, with ultra-low ESR and strong resistance to interference, keep the power stable and pure, joined by four ELNA SILMIC II, four Nichicon and six ELNA RA3 audio capacitors. Tulip-shaped, gold-plated NEUTRIK connectors resist oxidation and wear for precise, reliable connections.

Two processors for a smooth experience

A high-performance X2000 multi-core processor handles precise audio processing and stable, smooth playback with low power consumption, and a low-power ESP32-S3 SoC, with a dual-core Xtensa LX7 processor running at up to 240MHz, keeps the interface fast and responsive.

Retro design, five knobs and a remote

The K17 blends square and circle into one design, with a grille that dissipates heat quickly. Five knobs on the front switch it on and off, choose the output (PO+PRE, PO, PRE or LO), set the gain (L, M, H, SH or UH), and adjust the volume and menus; the volume and menu knobs also press, and their light rings have customisable colour and brightness, always on or pulsing. The custom 3.93-inch bezel-less touch screen (240 × 1,020) shows the working and output mode, track format and sample rate, EQ, volume, gain, network status, Bluetooth codec and time, and a swipe up or down brings up VU meters (except with DSD). The included infrared remote switches modes, picks EQ settings and adjusts the volume from your chair, and puts the K17 into standby for an instant wake-up. The FiiO Control app lets you change settings from your phone.

Protected against the unexpected

Headphone-amplifier temperature, transformer temperature, output overload, output DC and power-input overcurrent protection detect abnormal conditions and step in automatically, so you can listen with peace of mind.

Ways to use it

FiiO suggests six set-ups: a computer over USB with headphones and active speakers connected at the same time; Roon on a computer playing music from a NAS; an amplifier and passive speakers playing from an iPad over AirPlay; a digital audio player connected to the front USB port; a USB flash drive played through headphones or active speakers; and an analogue source fed through the PEQ to headphones or active speakers.

Good to know

• Before first use, check that the voltage switch underneath is set to 230V for the UK.
• The 3.5mm trigger input (nominally 12V, working from 5–15V) lets it switch on and off with the rest of your system. The ground selector switch and M4 grounding terminal help when you pair it with equipment that cannot connect to mains earth, and can reduce ground-loop interference.
• The rear USB-A port supplies 500mA, enough for a flash drive; a portable hard drive needs its own power.
• Which headphone output is best? FiiO says the 4.4mm and XLR4 balanced outputs are much the same and have more power than the 6.35mm socket, and recommends trying each with your headphones.
• There is no DLNA, and Bluetooth is for music only.
• In the box: K17, AC power cable, remote control, XLR4 plug cover, spare fuse, two USB cables, headphone plug adapter, quick start guide and warranty card.
• Compare it with the FiiO K15 and the studio-grade flagship FiiO K19, or its predecessor, the K9 Pro ESS.