The black Benchmark HPA4 is a 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.

THX-888 Headphone Amplifier    High Voltage, Current, and Power    Low Distortion, Noise, and Crosstalk    256-Step Balanced Relay Gain Control    Balanced and Unbalanced Line I/O    DC, Thermal & Short-Circuit Protection    Touchscreen Control    XLR 4-Pin Balanced Headphone Output    1/4" TRS Unbalanced Headphone Output    Designed, Assembled, Tested in the USA

The collaboration between Benchmark and THX features THX Achromatic Audio Amplifier (AAA) technology, which 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 extreme linearity. THX AAA allows the amplifier to reach its maximum output power and sound pressure level without producing the distortion that normally accompanies increased output levels in traditional amplifiers.

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 premium gold-contact relays. The gain control has 256 steps in 0.5 dB increments. It also features a balance control. Relay closures are precisely timed to deliver smooth volume changes. The HPA4 includes four independent 256-step attenuators: two for the headphone outputs and two for the line outputs. To make this all happen, the HPA4 includes a total of 64 precision relays.

The HPA4 is 100% analog and should be driven from an external D/A converter or analog source. It eclipses the performance of typical high-end preamplifiers by achieving much lower noise and distortion.

The THX-888 amplifier can 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 6W into 16 Ohms. Given these extreme capabilities, Benchmark has incorporated several protection systems to protect expensive headphones and the amplifier itself. These include DC, short-circuit, over-current, over-voltage, and thermal protection.

The bandwidth of the HPA4 extends from 0.01 Hz to over 500 kHz with a drop of only 3 dB. The 10 Hz to 20 kHz spectrum boasts a maximum variance of only -0.003 dB. 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 headphone output of the THX-888 amplifier features a 1/4" TRS and an XLR 4-pin. While both outputs deliver the full performance of the HPA4, the XLR4 is most ideal due to its lower contact resistance. The HPA4 features two balanced stereo inputs via XLR 3-pin jacks and two unbalanced stereo inputs via RCA jacks. The line amplifier provides one balanced stereo output, one balanced mono sum, and one unbalanced stereo output.

The touchscreen provides easy access to advanced features such as balance control, input level offsets, input names, screen dimming, remote control, and function locking. Help screens explain the special functions.

The volume control knob features a high-quality optical encoder that is rated for heavy use. An acceleration feature makes it easy to move through the 256 volume steps while maintaining 0.5 dB/step resolution. A press of the control knob toggles between headphone volume, line out volume, or both.

Two bidirectional 12V trigger ports can be used to link the HPA4 with external D/A converters and power amplifiers. The trigger signal controls the power-up and power-down sequencing of the entire audio system. The trigger ports are compatible with most industry-standard trigger input or output ports, but can communicate bidirectionally with other Benchmark products.

The HPA4 includes independent on-screen mute buttons for the headphone and line outputs. Both can also be muted with the volume knob or with the remote control (available separately). An on-screen -20 dB dim button instantly reduces the level by 20 dB, providing a temporary volume reduction and an easy return to the previous listening level. This control makes it easy to transition between a normal listening level and a background level. The dim function is also accessible from the remote control.

Inputs may be renamed and unused inputs may be disabled. Input levels can be trimmed to provide input-to-input level matching. Screen brightness is adjustable and timers can be set to dim or shut off the display. The screen can be locked to prevent access to advanced features.

The case features a milled faceplate and milled sides. Top, bottom, and rear panels are made from thick aluminum and feature a brushed texture. The HPA4 was designed, assembled, and tested in the USA.

Related Questions and Answers

Q: 1. How good is it for the Sony MDR-XB950-BT?

A: They should fit with just a little bit of compression for a snug, glove-like fit.

Q: 2. Does this lens transmit exif data to the camera?

A: The Voigtlander Ultron Vintage Line 35mm f/2 Aspherical Type II VM Lens lacks electronic contacts on the mount, so EXIF data would not transmit.

Q: 3. Is this an 18% gray?

A: According to Michael Tapes the designer, he states that it is an 18% gray.

Q: 4. is this case good for Beyerdinamic dt770 pro?

A: Yes, the SLAPPA HardBody Pro Full-Sized Headphone Case (Dimpled Polyurethane, Black) BH #SLHP07 is compatible with the Beyerdynamic DT 770.

Q: 5. Wil the AKG K533 mkII fit?

A: The AKG K553 MKII will fit in the SLAPPA HardBody Pro Full-Sized Headphone Case.

Q: 6. Is this case good for Hifiman Arya?

A: The SLAPPA HardBody Pro Full-Sized Headphone Case (Dimpled Polyurethane, Black) BH #SLHP07 is compatible with the following headphones below: Allen & Heath Xone 53 Audio Technica ATH-M50x Audio Technica ATH-Pro500MK2 AKG k 845BT AKG K 240 Semi-Open Beyerdynamic Custom One Pro Beyerdynamic DT 770 Bose AE2i Cortex CHP-2500 Denon AH-D2000 Fostex T-50RP Grado SR60i HiFiMan HE Series (400i, 400, 560, 6) JBL 700 Everest Logitech 930 5.1 wireless Marshall Major Headphones Monster Beats Wireless Monster Beats Pro Mr.Speakers Mad Dog ONKYO Maiden Audio On-Ear ED-PH0N3S Pioneer HDJ - 1000 Pioneer HDJ - 2000 Philips Fidelio L1 Polk Audio 4 Shot Playstation Gold Wireless Sennheiser HD 518 Sennheiser HD 650 Sennheiser HD 280 Sennheiser HD 201 Sennheiser HD 598 Sennheiser Urbanite XL Wireless Sennheiser PXC 450 Sony MDR-900 Sony MDR-V6 Sony MDR -V700 Sony MDR-7506 Sony MDR-1RBT Sony MDR-1a Sony PULSE Headset Elite Edition Sony MDR-XB950BT Superlux HD688B Shure SRH-440 Turtle Beach Ear Force 7 V-MODA Crossfade LP

Q: 7. Does this fit the ATH-M20x?

A: This is a large case. The ATH-M20X fit nicely.

Q: 8. Will this fit Sony WH-XB900N?

A: Yes.

Q: 9. whether this lens will work well with a canon eos R camera via the m-eosr adapter?

A: Yes, you can use a Leica M Lens to Canon RF-mount Camera. The lens and camera operations and exposure will need to be set on manual. Please review the following link to find some of our options available online. https://www.bhphotovideo.com/c/search?q=leica%20m%20to%20canon%20rf%20mount%20&sort=PRICE_LOW_TO_HIGH&filters=fct_a_filter_by%3A03_INSTOCK%2Cfct_lens-mount_1596%3Aleica-m

Q: 10. Would the B&O h9is fit?

A: I don't have B&O headphones bit it fits Focal Euphoria, Sennheiser 800s and Audeze LCD 2's which i beleive are larger. The B&O will be no problem.