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The M-504 has a solid reputation as a hefty, high-current power amp from Onkyo’s better era, and this asking price looks ambitious against the recent used market. With a median of US$1,100, a 25th percentile of US$997, and a 75th percentile of US$1,450, US$1,500 sits just above the top of the normal range, so it needs something special to justify it.
If it’s truly clean, fully original, and recently serviced, there’s still appeal here: these are respected for drive, authority, and a big, composed presentation. That said, at this level a buyer should want evidence of care, since vintage power amps can hide age-related service needs; without standout condition, accessories, or maintenance history, this is more of a premium ask than an easy buy.
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.
See all Onkyo listings on RADAR.
