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Unknown condition makes the price harder to justify, and at USD 719 this is an ambitious ask: it sits above the 75th-percentile comparable price of USD 637 and well above the USD 214 median from 38 recent listings. Unless it is genuinely mint, complete, and backed by a strong return policy, there is room to negotiate.
The Sigma Pro is a serious portable DAC/amp, with dual ESS conversion, Questyle’s current-mode amplification, Bluetooth, and useful 3.5mm, 4.4mm balanced, and 6.35mm headphone outputs. Its high-resolution PCM/DSD support and battery-powered flexibility make it unusually capable as both a desktop and travel unit. At this money, verify battery health, charging, display and controls, Bluetooth stability, and inclusion of the charger and accessories; a clean, complete example would be appealing closer to the market median than this listing’s ask.
Independent perspective — not a price guarantee. Always verify condition, accessories and provenance before purchase.
Questyle Audio emerged in December 2012 from Shenzhen, China, founded by Jason Wong, an innovator whose university experiments in 2006 sparked the company's signature Current Mode Amplification (CMA) technology. This patented approach, filed globally just 18 months after launch, revolutionized amplifier design by adapting current amplification from high-speed communications to audio, prioritizing lossless, high-fidelity playback. Rooted in China's tech hub and manufactured by Foxconn, Questyle quickly built a global footprint through relentless R&D focused on overcoming environmental and technical barriers to pure sound.
The brand specializes in premium digital-to-analog converters (DACs), headphone amplifiers, and integrated desktop solutions, with standout portable dongles like the M12 and M15 embodying CMA alongside ESS flagship chips for PCM 384kHz/32-bit, DSD256, and MQA decoding. Their lineup emphasizes minimalist elegance, from compact mobile amps to robust desktop DAC/headphone amps like the Q192, delivering effortless, high-resolution performance without gimmicks.
Questyle holds a confident position in the high-end portable and desktop hi-fi market, earning acclaim as a premium challenger to established names through superior build, explosive detail, and V-shaped dynamics. Audiophiles praise its trouble-free excellence and technological edge, cementing its reputation among discerning buyers seeking innovative, no-compromise audio gear.
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