The black Benchmark HPA4 is a 2 RU rackmount reference headphone/line amplifier designed to deliver pristine amplification of analog sources for audiophiles, mixing and mastering engineers, and music aficionados in homes, recording studios, and mastering suites. Resulting from Benchmark's collaboration with THX, the HPA4 features a THX-888 headphone amplifier for an output signal with high voltage, current, and power complemented by low distortion, noise, and crosstalk. Designed, assembled, and tested in the USA, it boasts a sturdy brushed aluminum housing with a milled faceplate and milled sides.
The rear-panel I/O includes two balanced stereo XLR inputs, two unbalanced stereo RCA inputs, XLR and RCA stereo outputs, and a mono XLR output. The front-panel offers two headphone outputs, one unbalanced 1/4" TRS jack and one balanced XLR 4-pin jack. Volume adjustments are executed via the 256-step balanced relay gain control, which uses increments of 0.5 dB. The integrated touchscreen allows convenient access to common functions such as input selection, dim, mute, and more. Built-in protection systems guard against potential damage from DC, short-circuit, over-current, over-voltage, and thermal issues.