The black Benchmark HPA4 is a 2 RU rackmount 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 and supplied remote control allow 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 and Wireless Remote    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 supplied remote control. 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. Will this work with the Canon Rebel T3?

A: Yes!

Q: 2. What about 5Dsr is that work with it?

A: Depends on if you will need the extra resolution, for printing or something like that.

Q: 3. I have the T6i. How do I set this up so that it takes the photo after 5 secs, or can it only do 2sec? I have the camera set at 5 sec, but it still takes the photo asap so I don't have time to put my arm down for self portraits Thanks!

A: Unfortunately this is limited to 2 second delay or immediate shooting. The other option is to go with a wireless radio system like the Vello FreeWave Wireless Remote Shutter Release linked here. https://bhpho.to/3o4aG14. The benefit of this is it does not need to be in line of site. Or you can go with the Vello Wireless ShutterBoss III linked here. https://bhpho.to/3f3ghki. This allows you to set any duration delay timer you wish.

Q: 4. Does this work with canon rebel t5i?

A: Yes, it does

Q: 5. Does this work for Canon 5D (non Mark II or III) just a regular 5D?

A: yes

Q: 6. Is it compatible with a eos m10

A: Yes, this remote is compatible with the Canon EOS M10.

Q: 7. Do you have to have direct line of sight for the remote to work?

A: Yes you have to be in front of the camera and no more than 20'.

Q: 8. do i need a clear line of sight for the remote to work?

A: Yes, the remote must be pointing at the camera's sensor (on the FRONT of the camera, just right of the lens. As long as you are in front, and not too far off to the right side (where the lens may interfere), it triggers well.

Q: 9. will RC-6 remote work with 1ds mark III?

A: No, the Canon RC-6 Wireless Remote Control is not compatible for use with the Canon EOS 1Ds Mark III DSLR camera.

Q: 10. will the Rc-6 wireless remote control work with the canon EOS M5 mirrowless camera if so how do I set it up. ?

A: According to B&H, that is an accessory for that camera. I don't have that camera, though.