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Selling a legendary Onkyo M-509 vintage power amplifier. A rare high-fidelity masterpiece from the golden era of audio, perfect for audiophiles and collectors. NOTE: THIS IS A 100V JAPANESE MODEL - A STEP DOWN TRANSFORMER IS NEEDED TO OPERATE THIS UNIT. THIS UNIT IS BEING SOLD AS-IS FOR PARTS OR REPAIR. NO GUARANTEES AS TO THE FUNCTIONALITY OF THIS AMPLIFIER. NO RETURNS FOR ANY REASON. SpecificationsPower output: 200 watts per channel into 8Ω (stereo)Frequency response: 1Hz to 100kHzTotal harmonic distortion: 0.01%Damping factor: 200Input sensitivity: 1.5VSignal to noise ratio: 94dBSpeaker load impedance: 4Ω (minimum)Dimensions: 480 x 191 x 439mmWeight: 31kgYear: 1982Local pick up / inspection / purchase available at Archer High Fidelity in Falls Church, VA. We are a vintage sales and service specialist covering the Washington DC metro area.All major credit cards accepted, as well as PayPal, check on clearing, and Venmo.Any other questions, please feel free to ask.
At US$295, this is below what the M-509’s vintage prestige and power rating usually justify, so it reads as a good buy rather than an ambitious ask. The original Japanese list price was ¥350,000, and comparable used examples commonly land well above this when they’re clean and working, so US$295 is solid if the amp is healthy and not cosmetically rough.
The appeal is straightforward: the M-509 is a serious 200W-per-channel-class Onkyo Integra amp with very low distortion and a reputation for a big, controlled, refined sound. If the listing is complete and serviced, the upside is strong; just verify that it powers up quietly, both channels are stable, and there’s no sign of relay or output-stage trouble, since vintage high-power amps are only bargains when they’re mechanically and electrically sound.
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.
