The Benchmark HPA4 headphone preamp/amplifier is based on the proprietary line-out amplifier and THX’s THX-888 AAA™ (Achromatic Audio Amplifier) headphone amplifier technology. The same technology is used in the AHB2 power amplifier. This technology achieves exceptional measurement levels with very low noise and distortion with near-perfect linearity. This headphone preamp/amplifier also features high power output, making it compatible with most headphones on the market, regardless of their impedance. The HPA4 uses all-analog circuitry and is therefore designed to work in conjunction with a DAC or external analog source. The front panel features a touch screen for easy access to parameters and settings. In terms of connectors, there are 2 balanced stereo XLR inputs and 2 stereo RCA inputs with stereo RCA and XLR outputs. In addition, there are two 12V 3.5mm trigger jacks, one XLR mono output and two headphone outputs: 6.35mm jack and 4-pin XLR.
THX-888 technology is capable of delivering high voltage and driving high impedance headphones with low sensitivity. The HPA4 delivers up to 11.9V into a 300-ohm load and up to 6W into a 16-ohm load. Given the extreme capabilities of its amplifier, Benchmark has built in protection systems to protect the equipment (DC detection, short circuit detection, overcurrent protection, overvoltage protection and thermal protection).
HPA4 has a bandwidth of 0.1 Hz to 200 kHz. This makes it a preamp/headphone amplifier capable of producing an extremely detailed and accurate signal.
The touch screen on the front of the HPA4 provides easy access to settings such as balance adjustment, input level offset, input names, screen brightness and function lock. The volume control knob is equipped with a high-quality optical encoder and has 256 volume levels with a resolution of 0.5 dB/step. Pressing this volume knob selects the desired output. In addition, the remote control enhances the user’s options.