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Amplifier is in really nice condition. Works beautifully. It has been loafing along for the past eight years driving my Paradigm Studio 20 bookshelf speakers in my bedroom system. I had it paired with the Matching P-304 Pre amp...which I have also listed here on ebay. I have enjoyed it on the weekends now and again and can report that it works perfectly. Listening to it as i write this listing. I have replaced the Meter lamps lately....I was a Copier and fax technician for years and so am very familiar with electronics and the use of a soldering iron. So the new owner need not be worried with the possibility of the meter lamps failing. Those meters are so beautiful to look at while listening. The amp performs as it should. It looks amazing. Very well cared for. A & B Channels work as they should. The amp is a high current design. It really sounds smooth and musical. Side wood panels look great. It is quite clean. It comes from a smoke free/pet free home. New owner should be quite pleased. This model amplifier has earned a much deserved reputation for musicality. Amp will be professionally packaged for safe transit. I will ship right out. Please see my feedback and buy with confidence. Thank you for your consideration.
At US$1,450, this Onkyo Integra M-504 is ambitious, sitting clearly above the 75th percentile of US$1,300 from eight recent comparable listings, with a median of US$1,050. While the 25th percentile drops to US$961, this asking price exceeds the top quartile, making it a hard sell for a buyer seeking fair value unless the condition is exceptional or accessories are pristine.
The M-504 remains a well-regarded vintage stereo power amplifier from Integra’s classic era (1987–1997), praised for its robust build and long, reliable manufacturing run. It delivers clean, powerful amplification that many consider “one of the best sounding vintage amplifiers,” often paired with the P-304 preamp for a complete system. If this listing includes original racks, manuals, or shows original-owner care, the premium may be justified; otherwise, it’s worth waiting for a unit closer to the US$1,050 median.
Independent perspective — not a price guarantee. Always verify condition, accessories and provenance before purchase.
Onkyo traces its roots to postwar Japan, founded in 1946 in Osaka by Takeshi Goda, an engineer at Matsushita Electric who envisioned high-quality Japanese loudspeakers. Initially established as Osaka Denki Onkyo K.K., the company began production in 1948 with the acclaimed ED-100 speaker featuring a 25 cm driver, quickly building a reputation through LP concerts and innovative designs that resonated with audiophiles.
The brand excels in premium home audio, renowned for AV receivers, hi-fi amplifiers, and surround sound speakers that deliver exceptional clarity and power. Its portfolio spans turntables, DACs, headphones, and cables, bolstered by acquisitions like Pioneer's home electronics division in 2015, enabling cutting-edge integrations such as internet radio and high-resolution streaming.
Onkyo holds a solid mid-tier position in the hi-fi market, prized by discerning buyers for reliable performance and value rather than ultra-high-end exotica. Despite bankruptcy challenges in the late 2010s, its revival under new ownership preserves a legacy of technological innovation and pure sound enjoyment, appealing to both vintage enthusiasts and modern home cinema setups.
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