Benchmark Goes Big With The HPA4 Headphone Amplifier

Benchmark is primarily known for their pro-leaning DAC series (now in their 3rd generation) in the audiophile circles.  Hot on the heels of a new power amplifier (AHB2, $3k) a new head amp made its debut at Canjam in Los Angeles this weekend. Dubbed the HPA-4 ($3k) and sporting a significant number of ins and outs, the standalone amp pays homage to the dual 3.5mm jacks offered on the popular digital converters but with several bonus features thrown into the mix.

At first glance the obvious jump is the somewhat rare inclusion of a LCD readout for a headphone amplifier. But not only is there an on-board display, said screen is actually touch sensitive as well. A heightened level of adjustments are offered in the simple but fairly deep setup screens. Balance, input selector, mute, and a -20dB pad for a quick quiet of approaching colleges or significant others can be found all within arms reach. Single ended and 4 pin XLR balanced are offered on the front panel as well as access to the stepped attenuator. From the show handout under the heading “Rotary Encoder”:

“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.”

And further down:

“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.”

The first question I asked was about the dreaded clicking noise that sometimes accompanies volume knobs of this type, but technical support manager Michael Siau assured me the design process kept this very hurdle in mind during R&D and none of this type of disruptive sound was found during my demo of the floor model – nicely done.

While $3k for a power amp isn’t unheard of in the two channel realm, that rate is a bit more rare in the personal audio space. The HPA4 seeks to make up some of that lead as a pre amp. The back side is fully armed with two sets of balanced inputs and two sets of SE. Further pushing the case is balanced mono connection for a subwoofer. Despite the inherently binary display screen, the new amp utilizes a 100% analog signal path and is THX certified with Achromatic Audio Amplifier (AAA) technology.

There is a separate option for a remote control and 12V triggers to coordinate with other components. Tech specs ramp up at 6 watts into 16 ohms and output impedance at “near 0 Ohms”. Its all played out in a tight package that doesn’t leave much out, either in internal spec terms or i/o connectivity for a desktop head amp. The HPA4 is available for reservation on Benchmark’s site with a projected ship date of June this year.

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