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This is a buyer’s market at US$100, because it sits below the US$110 25th percentile and under the US$119 median of recent comparable listings. For this model, that makes it a bona fide bargain rather than just a fair ask.
The MT-604 is well liked as a straightforward tube headphone amp: it’s a simple way to add a bit of warmth, drive harder-to-run headphones, and give a desktop system a more engaging presentation without spending much. At this price, the upside is solid if it powers up cleanly and includes the PSU and tubes; with condition unknown, I’d mainly verify noise, channel balance, and that both channels are healthy before jumping in.
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.
