xDuoo MT-604 Balanced Tube Headphone Amplifier

$143.65 $169

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Fully-balanced tube amp

xDuoo doesn’t do incremental improvements. They evolve by leaps and bounds. The MT-604 is a Class-A tube amp that doubles its predecessor’s tube count and channels, making for a fully balanced tube amp experience. 

Class-A amplifier

The MT-604 is a class-A amplifier. Using simple circuits that draw the same amount of current and consume the same amount of energy whether receiving a signal or not, this is the most straightforward of amplifier types. It isn’t subject to electromagnetic interference caused by digital components, so its total harmonic distortion and signal-to-noise ratio are exceptionally low.

53% more power than the MT-602

The MT-604 outputs up to 2000mW (32Ω) of power. That’s 53% more power than the MT-602--enough to drive even the HiFiMAN HE-4. 

Tube + transistor

A common complaint about tube amplifiers is their lack of high frequency response and resolving power. To overcome this, xDuoo added a rear transistor circuit capable of large dynamics, high speed, and resolving power. Tubes + transistor: the best of both worlds. 

XLR and 4.4 balanced input/output

The MT-604 is a fully balanced amplifier. Plug in any source into its XLR or 4.4mm balanced inputs, and enjoy rich, unhampered sound from its XLR or 4.4mm balanced outs. 

Independent left/right volume adjustment

Sound bias--the phenomenon of one driver being louder than the other--is a thing of the past with the MT-604. Independent left and right volume adjustments let you control each channel separately, ensuring perfectly equal volume across both headphone earcups.  

Built-in mute circuit

Anyone who’s ever plugged in their headphones before turning on their amplifier knows that many amplifiers make an ear-splitting “pop!” noise when turned on. Thanks to a built-in mute circuit, the MT-604 prevents this from happening, saving your ears and your patience.  

Interference-blocking chassis with sand-blasted texture

The aluminum alloy chassis offers a rugged defense against bumps, bruises, and electronic interference. The sand-blasted gray shell beautifully complements the striking red dials and atomic-era aesthetic of the tubes. 

Tubes will roll

Adventurous audiophiles will love swapping out the stock tubes for other tubes. Every model of tube has a different sound signature, enhancing or reducing warmth, detail, and soundstage. It’s a fun way to play with the sound signature of a single amp, often for less than $30 a pop. Just be sure to find a reputable dealer of tubes before buying. 

Product highlights

  • Tubes + transistor hybrid
  • Fully balanced amp
  • Four 6J1 tubes
  • Class-A amplifier
  • 53% more power than MT-602
  • XLR and 4.4mm balanced outputs
  • Independent left/right volume adjustment
  • Built-in mute circuit
  • Interference-blocking chassis
  • Switchable tubes


  • Power supply: DC12V/2A
  • Output power: 2000mW @32Ω 1kHz
  • Inputs: XLR
  • Outputs: XLR, 4.4mm balanced
  • Dynamic range: 85dBA @32Ω
  • Frequency response: 10Hz - 60,000Hz (±0.5dB)
  • Suitable headphone impedance: 16Ω - 600Ω
  • Gain: +15dB
  • S/N: 115dB
  • THD+N: ≤0.01% (@32Ω, 1kHz)
  • Size: 6.6” x 3.9” x 2.3” (17 x 10 x 6cm)
  • Weight: 1.2lbs (0.55kg)

What’s included

  • xDuoo MT-604
  • Power cord
  • AC adapter
  • User’s manual
  • Warranty card

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