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Douk Audio K5 USB DAC and Headphone Amplifier with Optical D/A Converter Review

A five-in-one desktop unit - USB DAC, headphone amp, preamp, SPDIF DAC and USB-to-optical converter - built on an ESS9038Q2M with PCM 384kHz/32-bit and DSD256 support. Dual headphone jacks deliver 560mW at 32 ohms with high and low gain modes.

3.63.6 out of 5 starsUpdated October 14, 2026
$79.99Price checked October 14, 2026
Check price at Douk Audio
Douk Audio K5 USB DAC and Headphone Amplifier with Optical D/A Converter

Our verdict

The K5 is easy to recommend as a first desktop DAC/amp at $79.99: an ESS9038Q2M with excellent measured performance, five different jobs in one box, DSD256 and 384kHz decoding, and dual headphone jacks with gain modes for anything from 16-600 ohms. The PURE switch that removes tone controls from the path is a purist touch. Just note the Windows 7 gap and that the knobs only affect the analog outputs.

Best for
Desktop listeners who want one small box to decode USB and optical audio and drive almost any headphone.
Skip if
You run Windows 7, or you need volume control applied to the optical/SPDIF output path.
Check price at Douk AudioHow we research

The Douk Audio K5 is a compact USB DAC and headphone amplifier priced at $79.99 that plays several roles at once: a high-performance headphone amp, a USB DAC, a preamp, a SPDIF DAC, and a USB-to-optical converter for transmitting audio from a computer to devices that only accept optical digital input, such as some CD players, amplifiers and active speakers.

The chipset pairs an ESS9038Q2M DAC with an SA9312 DSP, OPA1678 low-pass filter and SGM8262 amp. It decodes PCM up to 32-bit/384kHz and DSD256 over USB, and the measured performance is strong for the price: SNR above 121dB, a noise floor of only 3μV and THD of 0.0007%. Inputs are USB and SPDIF optical, while outputs cover optical, stereo RCA and the two headphone jacks.

Headphone listeners get dual 6.35mm and 3.5mm outputs delivering 560mW and 470mW at 32 ohms per channel, with high and low gain modes to match headphones from 16 to 600 ohms. Treble and bass controls have a midpoint position for a perfectly balanced default, and a bypass switch toggles tone processing off entirely for the purest sound. Power can come straight from a USB Type-C source with enough current (over 2A), otherwise the supplied DC 5V/2A adapter takes over. A combined volume/power button and colorful LED indicators for mode and sampling rate keep operation simple, all in a CNC-molded aluminum body.

Douk Audio ships worldwide with free and expedited shipping options at varying cost by country. Packages under 2kg travel by airmail in roughly 10-25 days, while orders over 2kg ship via DHL/UPS/FedEx in about 5-8 days, and any import duties or customs charges are the customer's responsibility. Returns are free within 30 days for a full refund, and every item carries a 1-year warranty. Exclusions cover orders placed by mistake, man-made damage or misuse, a change of mind, and anything outside the warranty terms.

What we liked

  • Five roles in one: headphone amp, USB DAC, preamp, SPDIF DAC and USB-to-optical converter
  • ESS9038Q2M decoding with strong numbers - SNR above 121dB, THD of 0.0007% and a 3μV noise floor
  • PCM 32-bit/384kHz and DSD256 playback over USB
  • Dual 6.35mm and 3.5mm headphone outputs with 560mW/470mW at 32 ohms and high/low gain modes for 16-600 ohm headphones
  • Tone controls with a PURE bypass switch that removes them from the path entirely, plus colorful mode and sample-rate LED indicators

Worth noting

  • Not compatible with Windows 7
  • The volume and tone knobs only control the analog outputs (RCA and headphone jacks) - they do not affect the optical/SPDIF path
  • Needs USB current above 2A to skip external power; below that the supplied DC 5V/2A adapter should be used

Questions before you buy

What is the USB-to-optical converter role for?

It lets the K5 take high-quality audio from a computer over USB and transmit it to devices with only a SPDIF digital input, such as some CD players, amplifiers and active speakers.

Which headphones can it drive?

16-600 ohms through the 6.35mm and 3.5mm outputs, with high and low gain modes; power is 560mW/470mW at 32 ohms per channel.

Is an external power adapter required?

If the USB Type-C source provides more than 2A of current, the K5 can be powered directly; below that the supplied DC 5V/2A adapter ensures proper performance.

Does the volume knob change the optical output level?

No - the volume and tone knobs only control the analog outputs, which are the RCA and headphone jacks.

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