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Quad 303 - Power Amplifier - Good
Why This One
Good condition - clearly used but works as it should
Fully tested - all applicable functions verified working
Legendary Class AB design with under 0.002% THD and 10A output current capability.
A 50W-per-channel amplifier at a significant saving over the new retail price.
Condition: Good
This Quad 303 is a good-condition power amplifier. It has passed our 8-point functional test, with 2 item(s) not applicable to this unit. Please review all photos carefully, as they provide an accurate representation of the cosmetic condition of the product.
What's Included
Quad 303
No additional accessories included
About This Model
The Quad 303 is a stereo power amplifier built around a fully complementary, symmetrical Triples Output Stage running in Class AB, paired with a custom 200VA toroidal transformer. It delivers 50W per channel into 8 ohms or 70W per channel into 4 ohms in stereo mode, and can be bridged to produce 140W into 8 ohms or 170W into 4 ohms. Total harmonic distortion is kept to under 0.002% at 1kHz, while a maximum output current of 10A means it handles demanding loads - including electrostatic speakers - with ease. Connectivity includes both RCA and XLR line inputs, stereo speaker binding posts, and 12V trigger I/O for system integration. The design traces its lineage to the original 1967 circuit that earned a 1969 Council of Industrial Design Award, updated here with modern components and robust protection against output shorting, overdriving, and disconnection.
A great opportunity to own a Quad 303 at this price point.
At US$236, this sits comfortably below the usual used-market center for a Quad 303, which lands at US$336 median, with the lower quartile at US$257 and the upper quartile at US$419. That makes this a strong-value asking price, not just “fair”; it’s in bargain territory for a well-kept example.
The 303 is respected for its smooth, unforced presentation, solid build, and classic Quad versatility, especially if you want a musical vintage power amp that can still partner well with modern systems. At this price, the main upside is simple: you’re paying well under typical market levels for a genuinely desirable piece. For a buying decision, condition and service history matter more than fear-mongering—if it’s quiet, original, and working properly, this looks like a very sensible buy.
Independent perspective — not a price guarantee. Always verify condition, accessories and provenance before purchase.
Quad, the venerable British hi-fi brand, traces its origins to 1936 in London, when engineer Peter J. Walker founded S.P. Fidelity Sound Systems, soon renamed the Acoustical Manufacturing Company. Relocating to Huntingdon in 1941 after wartime bombing, the firm shifted from public address gear to domestic audio amid post-war demand for superior sound reproduction. Walker's pioneering ethos—prioritizing "the closest approach to the original sound"—defined Quad from its early QA12 amplifiers, adopted by the BBC, to the iconic Quad I of 1953.
The brand excels in amplifiers and electrostatic loudspeakers, revolutionizing both categories. The Quad II power amplifier of 1953 introduced cathode coupling for vanishingly low distortion, while the 1956 ESL 57 delivered the world's first full-range electrostatic speaker, employing a massless film diaphragm for unparalleled transparency and transient speed. Quad advanced into solid-state with the 1967 303 and transistor designs featuring innovative "Triples" output stages, later expanding to integrated amps like the 99 series, moving-coil speakers, and modern electrostatic models such as the ESL 988 and 989.
Today, under the International Audio Group since 1997, Quad holds a prestigious position in the high-end market, revered by audiophiles for its unyielding pursuit of accuracy over trends. Its heritage components command vintage collector status, yet contemporary offerings maintain a niche boutique appeal among discerning buyers seeking refined, distortion-free reproduction that honors Walker's legacy.
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