In this article, I review the xDuoo MH-02 USB DAC and tube headphone amplifier. The MH-02 features a CS43131 DAC chip and dual 6J1 tubes. It’s priced at $149.
Disclaimer: This sample was provided by Shenzhen Audio for an honest review. All observations and opinions here are my own, based on my experience with the product.
xDuoo MH-02
Table of Contents


Design
The xDuoo MH-02 is a sleek, compact device with a modern design. It features two 6J1 vacuum tubes on top. The front panel includes 3.5mm, 4.4mm and 6.35mm headphone jacks, a large red volume knob that stands out against the gunmetal grey body and a red gain button that selects low and high gain modes.
The vertical slits on the front panel are for added visual interest and not actual vents. The top back left corner displays a logo resembling a mountain peak with three lines radiating from it, suggesting the brand.
On the rear panel are the Aux inputs and outputs, a USB-C input, the power switch and the DC12V input. The build quality feels great and personally, I love the aesthetic of the MH-02.

Functionality
Internally, the decoding is done by a Cirrus Logic CS43131 DAC chip which supports up to PCM 32Bit/384kHz, DSD256 and MQA. This is a hybrid unit, so in this setup, the tubes are used in the preamp stage to contribute to the overall tonal quality and character of the sound, while transistors provide the power needed to drive the speakers or headphones.
The headphone outputs deliver an impressive 1300mW of power which should be enough for pretty much any headphone you can plug into it. When you power on the unit, a built-in relay with a mute circuit prevents unpleasant pops and ensures the tubes operate under optimal conditions.
One oversight by the designers is the lack of an input select switch. The Aux input is overridden by the USB input, so to use an external DAC or source, you need to disconnect the USB cable. While this might not matter to most people, it could be a major inconvenience for those who want to regularly switch between Aux and USB inputs.

Sound
I tested the MH-02 with a variety of IEMs like the FiiO FD15 and Simgot EA500LM and headphones like the Simgot P2 Pro and Sennheiser HD650. It had more than enough power to comfortably drive any headphones I paired it with and maintained a black background, even when using IEMs.
I would describe the sound as fundamentally neutral, yet imbued with a subtle added dimensionality and richness due to second-order harmonics. This doesn’t create a warm, cozy sound but rather offers a slightly different presentation without significantly altering the tone. While that might disappoint some people looking for a more saturated sound, it will please others who want something more transparent.
The MH-02 adds a layer of complexity. Instruments and vocals occupy a more defined space within the soundstage. The overall tonality remains balanced, with a focus on accuracy and clarity. Therefore, the MH-02’s strength lies in revealing the nuances and intricacies of recordings so it is both engaging and revealing.

Verdict
At $149, the xDuoo MH-02 offers an attractive and powerful headphone amplifier with the audio benefits of tubes, and it also functions as a competent DAC. If you’re seeking an affordable entry point into the world of tube audio or a versatile DAC/amp combo, this one is easy to recommend.
Specifications
- Power supply: DC12V/2A
- Supported operating systems: Windows, Linux, Mac OSX, iOS, Android
- Sampling rate support: PCM 32-bit/384kHz, DSD256
- Headphone outputs: 6.35mm, 3.5mm, 4.4mm balanced
- Output power: 1300mW @ 32Ω
- Frequency response: 10Hz-60kHz
- Gain: +12/18dB
- THD+N: ≤0.8% (1kHz, 32Ω load)
- SNR: 118dB
- Crosstalk: ≥70dB
- Size: 4.7 x 3.1 x 1.6 inches (12 x 7.8 x 4 cm)
- Weight: 0.77 lbs (0.35 kg)