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KR Audio PX4 Valves/Tubes I purchased a quad of these rare KR Audio RK Anniversary Edition PX4’s and this the last pair. I’ve used them for approx 40hrs and they are superb tubes. Ive decided to stick with 45’s in my dac hence these are for sale. The RK Anniversary tubes are considered the best new production tubes around. Condition: As New / Mint Payment Method: EFT, PayPal Region/State: (QLD) Queensland/Australia By Gryffles 0 Comments Secure Ad AUD $835 Date: August 12, 20241 yr
Quad’s digital integrateds have a good reputation for clean, musical sound and sensible engineering, and A$835 in like new condition looks fair to slightly attractive for a KR PX4 with DAC. It doesn’t read as a steal, but it’s comfortably in the zone where a serious buyer can feel okay if this is the exact feature set they want.
The appeal here is simplicity done well: a compact all-in-one that should give you the Quad house sound without needing separate boxes. Like new condition is the real upside, especially if it includes the remote, box, and any original paperwork. At this level, I’d mainly confirm inputs, display, and that the DAC section is working quietly and properly, but otherwise it’s a 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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