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New, the HeadRoom Max sold for roughly US$1,333–US$1,600, so US$500 is a sensible used price rather than a steal. Your listing database puts it well above the US$238 median but below the US$599 75th percentile, making it fair for a tested example—provided this is the full-size Max rather than a less valuable variant.
This remains a desirable classic: a substantial solid-state amplifier with a real power supply, strong bass authority, very low noise, useful preamp pass-through, and both 1/4-inch and XLR connectivity. It was highly regarded in its day for revealing detail and driving suitable headphones convincingly. “Tested working” is worthwhile reassurance on an older unit, though I’d confirm both outputs, switches, volume control, and any processing features before paying US$500.
Independent perspective — not a price guarantee. Always verify condition, accessories and provenance before purchase.
Quantum Science Audio (QSA) emerged in early 2020 under the leadership of Steven Tsang, an electronic engineering expert with deep roots in audio consulting. Based in Scottsdale, Arizona, with ties to Hong Kong where Tsang honed his expertise, the brand quickly carved a niche through relentless innovation in power components. Drawing from over two decades of proprietary research, QSA embodies a fusion of technical discipline and audio obsession, prioritizing subtle yet profound system enhancements.
The company's focus centers on high-performance aftermarket fuses, including thermal, slow-blow, automotive, and specialized AC variants like inlets, outlets, and panel breakers. QSA also extends into power receptacles and related accessories, all engineered to eliminate so-called "bottlenecks" in signal paths. Their lineup spans accessible entry points at around $28 to ultra-premium models commanding exorbitant prices, reflecting escalating tiers of advanced materials and quantum-inspired treatments.
In the hi-fi market, QSA occupies a polarizing boutique position among high-end enthusiasts, celebrated by some for transformative sound improvements in power delivery. Top models attract audiophiles chasing marginal gains, though skeptics dismiss the claims as overreach amid long production lead times. This niche status suits discerning buyers open to experimental upgrades in an otherwise crowded field.
See all Quantum Science Audio listings on RADAR.
