HPA4 - Headphone Amp & Preamplifier

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  • Stereophile "A" Recmmended Component
  • at home as preamplifier in a $100,000 system
  • realistic and fatigue-free listening
  • high voltage, high current and high power
  • more than enough power to properly drive any headphone.
  • 100% analog signal path
THX AAA™ reduces harmonic, intermodulation, and crossover distortion by 20 to 40 dB to guarantee a realistic and fatigue-free listening experience. It accomplishes this using a patented feed-forward topology to null conventional distortion and noise mechanisms, resulting in the world's most linear amplifier. THX AAA allows the amplifier to reach its maximum output power and sound pressure level (SPL) without producing the distortion that normally accompanies increased output levels in traditional amplifiers.

Featuring the flagship THX-888 amplifier design, the revolutionary HPA4 headphone amplifier incorporates the same THX AAA technology that Benchmark uses in the AHB2 power amplifier. The HPA4 delivers sonic perfection. Hear the music without any contamination from electronic noise or distortion. The HPA4 delivers power, audio fidelity, speed and accuracy over an utterly silent background.


The Ultimate Line Amplifier
Home Theater and High Fidelity - Best High-End Preamplifier Award
The THX-888 amplifier is driven by a Benchmark line amplifier that features relay gain control, relay input selection, and relay muting. The line amplifier incorporates the finest gold-contact relays available. The gain control has 256 steps in 0.5 dB increments. It also features a balance control. Relay closures are precisely timed to deliver silky-smooth volume changes. No other relay gain control offers this level of precision and performance. The HPA4 includes 4 independent 256-step attenuators: two for the L&R headphone outputs, and two for the L&R line outputs. To make this all happen, the HPA4 includes a total of 64 precision relays.

100% Analog Signal Path
The HPA4 is 100% analog. It is designed to be driven from an external D/A converter or an external analog source. The HPA4 is designed to provide the ultimate analog signal path between inputs and outputs. The HPA4 eclipses the performance of typical high-end preamplifiers by achieving much lower noise and distortion.

High Voltage, High Current and High Power
The THX-888 amplifiercan cleanly deliver high voltage into low-sensitivity high-impedance headphones and it can cleanly deliver high power and current into low-impedance headphones. The HPA4 delivers 11.9 Vrms into 300 Ohms and 6 Watts into 16 Ohms. Given these extreme capabilities, Benchmark has incorporated several protection systems to protect expensive headphones and the amplifier itself. These include DC detection, short-circuit detection, over-current protection, over-voltage protection, and thermal protection.

Speed and Precision
The bandwidth of the HPA4 extends from 0.01 Hz to over 500 kHz. This means that the HPA4 delivers very precise amplitude and phase accuracy over the entire audio bandwidth. Wave shapes are accurately reproduced, and the entire spectrum is delivered with precise timing. The HPA4 will deliver musical overtones with life-like accuracy. This means that musical instruments are rendered without changing their sonic character.


Type Headphone and Preamp
Inputs  2 pair XLR, 2 pair RCA
Outputs 1 pair XLR, 1 pair RCA
Number of Chassis 1
Dimensions 8.7in x 3.9in x 8.3in
Weight 3.6 kg



  • HPA4 unit
  • remote control
  • Australian power cable
  • manual


  • delivered <5 business days from purchase
  • free shipping
HPA4 - Headphone Amp &amp; Preamplifier
HPA4 - Headphone Amp &amp; Preamplifier
HPA4 - Headphone Amp &amp; Preamplifier
HPA4 - Headphone Amp &amp; Preamplifier
HPA4 - Headphone Amp &amp; Preamplifier
HPA4 - Headphone Amp &amp; Preamplifier
HPA4 - Headphone Amp &amp; Preamplifier

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