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Comes loaded with General Electric Jan 5654w tubes in place of the generic Chinese 6j1 stock tubes/ with power supply and boxesTop highlights Warm tube sound combined with powerful transistor drivePowers headphones from 16Ω to 600Ω impedance range2000mW output handles demanding headphones effortlessly Summarized from product informationAbout Tube + Transistor Hybrid amplifier: Front tube amplifier and rear transistor combine the advantages of two amplifier circuits to achieve the ideal sound effect and make you immersed in the happy atmosphere of musicTube Amplifier: Adopt four 6J1 tubes for pre-amp, making voice sweet and exquisiteTransistor for Class-A amplifier: Adopt transistors for class A buffer, output power up to 2000mW,can easily drive many kind headphones (Suitable Headphone Impedance: 16Ω~600Ω)XLR and 4.4mm balanced input/output: It has XLR and 4.4mm balanced input, 4-pin XLR and 4.4mm balanced output, rich and diverse interfaces, suitable for many kinds of balanced headphonesIndependent adjustment of left and right channel volume: This unit is designed to adjust the volume of the left and right channels separately to reject the sound bias problemBuilt-in Mute Circuit: It built-in relay for mute circuit when turn on amplifier to avoid POP noise and make sure the tube is worked at its best conditionTop highlights MT-604 is a small balanced tube headphone amplifier. It adopts four 6J1 tubes for pre-amp with warm timbre, the post-amp is adopted high quality transistors for class A buffer,which can easily drive various low-impedance headphones and greatly enhance the sound field dynamics. The coupling capacitance applies Japanese Nichicon for high-end audio creating clear, sweet sound. The combination of the tubes and transistor bring up the sweet note of the former and the sense of speed of the latter, fully integrating the advantages and charms of both. Science knowledge About tube transistor hybrid amplifier: Tube, has its unique sound, the sound is sweet and soft, warm and durable, the music feels good, and the atmosphere is good;its shortcomings are the transient response to high frequency, the resolution is not as good as the transistor amplifier, listening to some symphony and other songs Especially obvious. Transistor,the advantages of transistor power amplifier are large dynamics, fast speed, high resolution and strong driving force,which is especially suitable for the performance of more dynamic music; its shortcomings are low frequency. The sound is not soft enough, and the high frequency sounds are sharp and dry. Therefore, the pre-amp used tube and post-amp used transistor, combining the advantages of these two power amplifier circuits to achieve the ideal musical effect, you can devote yourself to the joyful atmosphere of music. Product Features Adopt four 6JI tubes for pre-amp, making voice sweet and exquisite. Adopt transistors for class A buffer, so it can easily drive any kind earphones with strong load capacity. Use ELNA capacitors specially designed for audio as coupling capacitors. Adopt Nichicon capacitor specially designed for audio as the filter capacitor. It built-in mute circuit when turn on amplifier to avoid POP noise and make sure the tube is worked at its best condition. Use aluminum-shielded case to prevent external interference noise Parameters Power Supply: DC12V/2A Output Power: 2000mW(1KHz,32Ωload) Dynamic Range: 85dBA(32ohm) Frequency Response: 10Hz~60KHz (±0.5dB) Suitable Headphone Impedance: 16Ω~600Ω THD+N: ≤0.01% (1KHz,32ΩIoad) S/N: 115dB Gain: +15dB Size: 17*10*6cm Weight: 0.55kg Package List MT-604 AC Cable Adapter User's Manual Warranty Card
US$140 is a bit above the US$110 median and just over the US$135 75th percentile, so this is on the ambitious side rather than a bargain. It’s not wildly out of line, but it only makes sense if the unit is genuinely clean, well cared for, and comes with useful extras or strong proof of provenance.
The MT-604 has a solid reputation as a warm, listenable tube hybrid that adds a bit of body and ease without getting fussy, so it’s an appealing pick if you want a tube-flavored desktop amp that stays friendly with a lot of headphones. At this price, I’d want the original power supply, no hum or channel imbalance, and confirmation that the tubes are healthy; if those boxes are checked, it’s still a reasonable buy, just not a standout deal.
Independent perspective — not a price guarantee. Always verify condition, accessories and provenance before purchase.
xDuoo is a Shenzhen, China-based audio brand that emerged from the country’s fast-growing hi-fi manufacturing ecosystem. Its exact founding year is not consistently stated in the sources available here, and no founder is prominently verified, but the company is widely presented as Shenzhen xDuoo Technology Co., Ltd., with roots in OEM/ODM production before building its own consumer-facing identity.
The brand is best known for headphone amplifiers, DAC/amp combos, portable DACs, tube hybrids, and other desktop-and-portable electronics aimed at personal audio enthusiasts. xDuoo’s lineup has included tube headphone amps, balanced amplifier designs, digital-to-analog converters, and all-in-one sources, typically positioned for headphones rather than loudspeakers or turntables.
In the market, xDuoo sits in the value-to-mid-tier audiophile segment, with a reputation for offering ambitious feature sets, lots of connectivity, and occasional tube-flavored designs at relatively accessible prices. It is not generally considered a luxury or vintage-collector brand, but rather a practical, performance-driven Chinese hi-fi maker with a strong presence among enthusiasts seeking high features per dollar.
See all xDuoo listings on RADAR.
