Regarded as the world’s Ultimate Line Amplifier, the HPA4 is the result of a groundbreaking collaboration between Benchmark Media Systems and THX Ltd.

Key Features

• THX-888 (AAA™) Headphone Amplifier

• Benchmark Line Amplifier

• 256-step fully balanced relay gain control (0.5 dB steps)

• Precision-timed relay closures

• Precision metal film resistors

• Gold-contact relays

• Balanced and unbalanced I/O

• 6 watts into 16-ohm headphones

• 11.5 Vrms into 300-ohm headphones

• Short-circuit protection

• DC protection

• Over-voltage and over-current protection

• Thermal protection

• Touchscreen control

• IR remote control (optional)

• 2 balanced stereo line inputs

• 2 unbalanced stereo line inputs

• 1 balanced stereo line output

• 1 unbalanced stereo line output

• 1 balanced mono sum output

• 2 bidirectional 12V trigger ports

The HPA4 is the first headphone and line amplifier to incorporate THX’s Achromatic Audio Amplification (AAA™) technology. This innovation reduces harmonic, intermodulation, and crossover distortion by up to 40 dB, using a patented feed-forward topology that nullifies conventional distortion and noise mechanisms.

With the HPA4, Benchmark and THX have created a headphone and line amplifier that achieves maximum output and SPL without distortion, delivering exceptional power, audio fidelity, speed, and accuracy, all with a silent, clean backdrop.