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Recently serviced and working well. 200wpc at 8 ohms.
The early-1970s generation matters here: this is a genuinely vintage, high-powered solid-state design rather than a current replacement model. At USD 1,500, though, the ask is ambitious—well above the comparable-listing median of USD 448 and 75th percentile of USD 935. It only starts to make sense with exceptional restoration, documented performance, or unusually original, collector-grade condition.
The Stereo 400 remains appealing for its muscular 200 watts per channel, robust heat sinking, flexible 4–16-ohm drive, and useful protection circuitry; it can also run mono at substantial power. That makes it a compelling match for inefficient speakers or listeners who enjoy classic American engineering. At this price, insist on proof of service, stable operation, clean output, and working protection circuits: an unrestored example is not a buying opportunity, while a properly rebuilt one may justify some premium—but USD 1,500 still requires a very special specimen.
Independent perspective — not a price guarantee. Always verify condition, accessories and provenance before purchase.
Dynaco emerged in 1955 from Philadelphia, Pennsylvania, when hi-fi pioneer David Hafler partnered with engineer Ed Laurent to form the Dyna Company. Hafler brought expertise from his earlier Acrosound venture, which produced high-quality output transformers starting in 1950. The duo targeted the burgeoning hi-fi market with affordable, DIY-friendly kits, launching the Mk II 50-watt tube amplifier shortly after incorporation and relocating to a former chocolate factory for expanded operations.
The brand specialized in tube amplifiers that defined its legacy, including the iconic Stereo 70—over 350,000 units sold—alongside models like the Mk III. Dynaco expanded into FM tuners such as the FM-1, bookshelf speakers like the A-25, solid-state amps, and innovative systems like the Dynaquad for simulated four-channel sound. Late-1970s efforts included the Phase III speakers, though the company shifted toward kits and components emphasizing value and performance.
Dynaco holds a revered position as the era's top-selling tube amp maker, beloved by budget-conscious audiophiles for reliable, high-value hi-fi. Liquidated in 1980 after Hafler's sale to a toy firm, its vintage gear remains a collector's staple, with later revivals by Panor Corporation producing replicas for tube enthusiasts seeking that classic warmth and build-it-yourself appeal.
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