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DEQX HDP-4 Digital Signal Processor I'm trying to sell my DEQX HDP-4 that I am using for the crossover for my active VAF I-66's. Go to the DEQX website and look under legacy products for a full description. This is a pretty powerful tool for setting crossovers. If required, you can arrange a session with DEQX to have them set everything or have a crack yourself. It is a fully fledged DAC/preamp as well so it can be used to streamline a system. With me having another HDP-4 for the center/sub, I need to look at ways of reducing the cabling/device count, so I will be using the money to install p
This is a fair ask, leaning a touch ambitious: at A$3,000, it sits above the listed median of A$2,566 and also above the A$2,784 75th percentile, so it’s not a bargain on price alone. That said, it’s not wildly out of line for a niche, well-sorted processor if the condition is genuinely clean.
What makes it worthwhile is the DEQX appeal itself: these units are valued for serious room correction, crossover flexibility, and the kind of digital control that can unlock a very polished active or hybrid system. At this price, I’d want confidence in functionality, included accessories, and any history of servicing or firmware support; if those check out, it can still be a smart buy for a buyer who knows exactly what they want.
Independent perspective — not a price guarantee. Always verify condition, accessories and provenance before purchase.
DEQX is an Australian digital audio specialist founded in the mid-1990s as Clarity EQ Pty Ltd and formally established in 2001 by Kim Ryrie, the legendary co-founder of Fairlight Instruments. Ryrie's pedigree in pioneering digital audio technology—Fairlight revolutionized music production in the 1980s through its groundbreaking sampling instruments—directly shaped DEQX's engineering philosophy and access to world-class design talent. This heritage positions DEQX as a company with deep roots in digital signal processing innovation.
DEQX specializes exclusively in digital pre-amplifiers and audio processors engineered around speaker calibration and room correction. Their current Gen-4 lineup features integrated systems like the LS200 and flagship pre-amplifiers such as the Pre-8, all built on multi-core 64-bit processing architecture. Rather than traditional component categories, DEQX's core offering centers on digital correction technology that compensates for loudspeaker distortions and phase errors, reconstructing audio signals with microsecond precision to achieve time-coherent reproduction.
DEQX occupies the high-end niche market, targeting discerning audiophiles who prioritize measurement-based accuracy and digital processing sophistication over conventional analog approaches. Over 95 percent of their products are exported globally, reflecting strong international recognition among serious listeners. The brand has cultivated a reputation as a specialist tool for those viewing speaker calibration as essential to achieving reference-quality sound, positioning itself distinctly within the premium segment where technical innovation and measurable performance command premium pricing.
See all DEQX listings on RADAR.
