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Tested and Working. This was pulled from a working environment. Please look at all pictures before purchasing, only what is included in pictures is included in sale.Will ship same day purchased in a professionally packaged box. (D)S102B SS
US$550 is a solid buy versus this set of recent comps: it lands below the US$649 median and comfortably under the US$950 75th percentile, though not quite a true bargain versus the US$510 25th percentile. In other words, it’s priced in the lower half of the market, close enough to value territory that I’d call it attractive if the unit is complete and working.
The reason this is worth a look is that Dynaco mono blocks have a real following for their authoritative, musical presentation and strong upgrade path, so even a plain, used example can be a rewarding piece to own. At this price, the main upside is getting into a respected classic without paying top-of-market money; just verify transformer health, channel symmetry if applicable, and whether any restoration has already been done.
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.
See all Dynaco listings on RADAR.
