Benchmark HPA4 headphone amp in black
Rear panel of Benchmark's HPA4 headphone amplifier
Benchmark HPA4 High Resolution Headphone Preamp

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

£3499.00 inc VAT
ETA 1-2 WEEKS
SKU BM-HPA4/B
EAN 602573174142

  • 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
  • Touch Screen 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

It is the first headphone and line amplifier to feature THX’s Achromatic Audio Amplification technology (or AAA) and reduces harmonic/intermodulation/crossover distortion by up to 40dB. The reduction is achieved by utilising a patented feed-forward topology which nullifies conventional distortion and noise mechanisms.

With HPA4, Benchmark and THX have produced a headphone and line amplifier capable of technically reaching maximum output and SPL without the usual side effect of distortion, delivering power, audio fidelity, speed and accuracy onto a silent canvas.

THD < -125 dB (0.00006%)
SNR 135 dB, unweighted, 20-20 kHz (> 131 dB THX)
SNR (A-Weighted) 137 dB (> 135 dB THX)
Frequency Response -0.003 dB at 10 Hz, -0.001 dB at 20 kHz
Impedance 60 Ohms (near 0 Ohms THX)
Output Noise < 1.9 uV at Unity Gain, 20-20 kHz (< 2.45 uV THX)
Max Input 20 Vrms (+28 dBu)
Max Output 20 Vrms (+28 dBu)
Crosstalk < -133 dB @ 1 kHz, -116 dB @ 10 kHz
Dimensions 220 x 99 x 212mm, 3.62kg