NEW: xDUOO MT-04 Class-A Tube Headphone Amplifier
MT-04 hybrid Class A headphone amplifier
The MT-04 is a balanced hybrid headphone amplifier that combines two 6H3 vacuum tubes with a transistor-based Class A output stage. The tubes handle preamplification, while the transistors supply the current needed to drive headphones. With balanced and single-ended connections, two gain settings, and up to 2200mW into 32Ω, it accommodates a range of headphones and desktop audio sources.
Tube preamplification with Class A power
The MT-04 divides amplification between two stages. The two 6H3 tubes shape the signal before it reaches the output stage, lending warmth and body to vocals and instruments. The transistor-based Class A stage handles headphone power delivery, with rated output reaching 2200mW into 32Ω through the balanced connection and 1800mW into 32Ω through the single-ended connection.
Connections for balanced and single-ended sources
RCA, balanced XLR, and balanced 4.4mm inputs provide connections for DACs and other line-level sources. Headphones connect through a front-panel balanced 4.4mm output or a single-ended 1/4-inch (6.35mm) output. Specified balanced-output performance includes a 125dB signal-to-noise ratio and 85dB crosstalk performance.
Two gain settings for different headphones
A front-panel switch selects between +12dB and +18dB gain, allowing the amplifier’s signal gain to be matched to headphone sensitivity and source output level. The rotary volume control then adjusts listening level within the selected gain setting.
Capacitors and an external ground connection
ELNA audio coupling capacitors serve the signal circuit, while Rubycon filter capacitors support power-supply filtering. A rear-panel ground terminal provides an external grounding point to help address static interference and hum associated with an ungrounded enclosure.
Tube warmup and circuit protection
A relay protection circuit provides a 30-second startup delay, giving the tubes time to warm up before listening. The circuit also suppresses switching pops and automatically cuts power in response to overload or short-circuit conditions to help protect the amplifier and connected headphones.
