FiiO K9 Desktop Headphone Amp/DAC - Standard Edition

The FiiO K9 is a truly balanced desktop DAC and headphone amplifier. Two ESS ES9068AS DACs, one per channel, feed two THX AAA 788+ amplifiers that deliver up to 2,000mW per channel into 32Ω and 780mW into 300Ω from the 4.4mm and 4-pin XLR balanced outputs, with a 6.35mm output alongside. USB, optical, coaxial, analogue and LDAC Bluetooth inputs, RCA and XLR outputs for speakers or another amplifier, and a linear power supply all fit in its aluminium body. It won a CIHE EHA 2023 Silver Award and a VGP 2024 Summer Life Style award.

Two DACs, one for each channel

Two ES9068AS DACs handle the left and right channels and form the high-quality core of the K9, decoding PCM up to 768kHz/32-bit and DSD512 over USB. Listen to your favourite playlist and be immersed straight away.

THX AAA 788+: power for any headphone

The K9’s ace up its sleeve is the THX AAA 788+ amplifier, giving an extraordinary undistorted (1% THD+N) output of up to 2,000mW per channel at 32Ω and 780mW at 300Ω from the balanced outputs. Low- or high-impedance, anything from 16Ω to 600Ω, the K9 drives your headphones with aplomb, and three gain levels match it to them: low for sensitive in-ear monitors, high for less sensitive over-ear headphones.

Truly balanced, from start to finish

From the DACs through the volume control to the amplifiers, every part of the K9 is truly balanced, which greatly reduces crosstalk for a more authentic sound. The desktop-grade six-stage audio circuit (I/V conversion, OPA1612 low-pass filter, NJU72315 volume control, OPA1602 buffer amplifier, pre-amplifier and THX post-stage drive) is designed for a pure, delicate yet rich sound.

Clean, plentiful power

“Electricity is the mother of sound”, as FiiO puts it. A customised linear transformer works with four massive 4,700µF capacitors to provide clean, continuous power. The digital and analogue sections are powered separately to reduce interference, each stage of the audio circuit has its own ultra-low-noise LDO regulator, and the circuit board is partitioned to keep the power supply, signal and analogue sections fully apart, protecting the integrity of the audio signal.

Precise clocks and a flexible USB input

Accurate, stable dual-mode clock management lets the K9 play high-resolution audio with great fidelity, as if you were there with the performers. The XMOS XUF208 USB receiver supports both UAC 2.0 (with a driver where your computer needs one) and plug-and-play UAC 1.0, for devices such as the PS5; switch between them in the FiiO Control app.

Hi-res Bluetooth

A Qualcomm QCC5124 Bluetooth 5.1 receiver supports LDAC, aptX Adaptive, aptX HD, aptX Low Latency, aptX, AAC and SBC, so you can listen to music, watch videos and play games from your phone with high quality and low latency.

Every connection you need

Five inputs (USB, optical, coaxial, line and Bluetooth) are chosen with the input button and shown by lights on the front. Line covers both the RCA and the 4.4mm balanced inputs; if both are connected, the 4.4mm takes priority. An output switch sets what is active:

Horizontal or vertical, with a weighty knob

The K9 follows the well-received design language of FiiO’s other desktop units. The all-aluminium body is made with an integrated stretching and CNC process for strength and a precise finish, and with the included stand it works upright or flat, wherever it suits your desk. The iconic, weighty volume knob uses ADC curve reconstruction for 120 precise, smooth steps with minimal noise and minimal difference between the left and right channels.

Lights that tell you what’s playing

RGB lights around the knob add personality to your desk and show the sample rate (48kHz or below, above 48kHz, or DSD) and the Bluetooth codec, each in its own colour.

More with the FiiO Control app

Connect your phone over Bluetooth and the FiiO Control app adds more: digital filters, the indicator lights, channel balance (12 steps of 0.5dB either way), EQ and UAC mode. The EQ has seven preset styles and three parametric EQs you can set yourself; it works in Bluetooth mode only.

Protected and upgradeable

Three protection systems (overheating, overload and DC protection) keep the K9 and your headphones safe, so you can listen without worry. Firmware for the system and Bluetooth can be updated over USB.

Good to know

• FiiO’s step-up model is the K9 Pro ESS; for a smaller, simpler balanced DAC/amp, the FiiO K7.
• To connect a phone over USB, use a USB-B to USB-C cable (a computer USB cable is included).
• In the box: K9, power cord, 6.35mm to 3.5mm adapter, USB cable, six feet pads, spare fuse, vertical stand tray, quick start guide and voltage selection card.