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Condition is unknown, but at US$975 this sits just below the US$990 25th percentile and well under the US$1,050 median, so it reads as a solid-buy price rather than a stretch. It is not a screaming bargain, but it is comfortably on the buyer-friendly side of the market for this amp.
The M-504 is a respected late-’80s/’90s Onkyo power amp known for strong drive, a clean, authoritative presentation, and enough current to make demanding speakers wake up. If the unit is clean, unmodified, and has been serviced or at least behaves quietly, the value is there; at this level, the main thing to confirm is basic health rather than hunt for a cheaper headline price.
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.
