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Iconic Onkyo power amp with Large dual VU meters. Doth meters and all lights function properly. This power amp had a 10 year run. Crazy long!!. Sound presence is outstanding. One hundred sixty five watts per channel. If purchased and not satisfied, buyer will receive a full refund but need to pay the return shipping.
The M-504 remains one of Onkyo’s more desirable vintage power amplifiers: a handsome, heavily built dual-mono design with 165 watts per channel and plenty of headroom. At US$875, this is a strong deal—just below the US$878 25th-percentile mark and well under the US$1,000 median from 19 comparable listings. Assuming it is functional, the price is notably attractive.
Its appeal is the combination of muscular drive, clean detail, smooth presentation, excellent channel separation, and those distinctive front-panel meters. It should suit demanding 4–8-ohm speakers well, though it is large, heavy, and decades old. Before buying, confirm both channels, protection behavior, meter illumination, speaker-selector operation, and the condition of the power switch; otherwise, this looks like a genuine buying opportunity rather than merely a fair listing.
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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