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At this age, the Series II is a mature, superseded design rather than a current-generation buy, so timing matters mainly because condition and service history now outweigh the badge. At USD699, it is clearly ambitious: the 99-listing comparison puts the median at USD238 and the 75th percentile at USD600. That price needs unusually strong provenance or exceptional condition to make sense.
The amplifier itself remains a serious piece: five identical Class AB channels, substantial power delivery, individual channel level controls, and the smooth, slightly warm presentation B&K is known for. It is a particularly good match for demanding home-theater speakers and remains attractive if you need real current capability rather than a lightweight modern multichannel amp. Still, with condition listed unclearly, this is a buyer-at-market-top proposition; verified testing, clean operation, and ideally service records would be essential before paying USD699.
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.
