"The HPA4 combined with the Benchmark AHB2 power amplifier ranks as the quietest rig I've heard (or not heard). Even with the gain up to full with no signal, there is no hiss, hum, or buzz, even when I placed my ears within a in inch of the drivers on 89 dB sensitive loudspeakers."
"As a headphone amplifier, the HPA4 was first rate. Whether it was my most power-hungry headphones, which currently are the new Abyss Diana Phi, or my most sensitive IERs, such as the Empire Ears Phantoms, there was no added noise or lack of adequate gain."
"The Benchmark HPA4 exhibits virtually no noise, whether employed as a stereo preamp or headphone amplifier, and his highly transparent, with no audible colorations."
"The HPA4's front panel is a simple affair, with an on/off button on the extreme left side followed on the right by quarter-inch stereo and XLR balanced headphone connections and a large volume control that has four independent 256-step attenuators in half-decibel increments. This permits the volume level adjustments for the line level and headphone outputs to be completely independent from each other. The HPA4 also has a full color touchscreen for setup and control."
"The front panel controls offer several welcome features, including the ability to control both the headphone and line level outputs separately or ganged together. Unlike many preamp/headphone amplifiers, which automatically mute the line level when a headphone is plugged in, the HPA4 gives users the option of using both at the same time."
"In addition to its pair of stereo outputs, the HPA4 has one more output: a line-level summed mono, which could be useful in connecting a subwoofer if yours doesn't have stereo inputs."
"The HPA4 occupies a unique place, not only due to its features and performance, but also its price. Sure, there are plenty of decent line-level preamplifiers, DACs with built-in volume controls, and scads of headphone amps, but to get the same level of ergonomics and performance as the HPA4 for the same money from separate components could be a challenging proposition, depending on your needs."
"Benchmark calls the HPA4 a "Reference stereo headphone amplifier and reference line amplifier," and I found no reason to dispute this. It performed at reference level with whatever I threw at it. It is ergonomically elegant with a well-laid-out remote and front panel controls. Also, its headphone amplifier was able to support a wide variety of headphones and is the first component to utilize THX Achromatic Audio Amplifier (AAA) technology."
"If you are looking for a preamplifier/headphone amplifier that you can live with happily for a long time, you should consider the Benchmark HPA4 at the top of your must-audition list."
- Steven Stone, HomeTheaterReview.com
"I don't think it is sterile sounding at all ... it is very neutral."
"In the studio, neutral, flat and detailed are on the top of my list."
"The HPA4 is speeding up my work, helping me make better decisions."
- Ken Jacobsen, Ken Jacobsen Music
"It has already been noted in previous reviews that the professional market often offers products that may also be of interest to the 'ordinary' consumer. In Japan in particular, home systems often consist of a mix of consumer equipment and (vintage) professional items."
"Benchmark was founded in 1983 and started building professional audio equipment."
"The goal, from the outset, is to build sound-transparent equipment of the highest quality. The employees are musicians, audiophiles and audio technicians. So sound quality is top notch."
"The HPA4 and LA4 are preamplifiers and largely identical. The HPA4 also has a built-in headphone amplifier."
"The Benchmark HPA4 and LA4 preamps deliver a very high quality neutral and transparent signal."
"Developed from a professional focus on sound reproduction, they bring the essence of the recording closer to the listener."
- Ruud Jonker, FWD Magazine, fwd.nl
"Before I dig into the sound of the LA4 it is important to know that it employs a wide bandwidth design. The LA4’s bandwidth is specified at 0.2 Hz to 500 kHz."
"Most of the wide bandwidth designs I have heard exhibit ... a purity in tone with superb timing and speed ... the LA4 proved to be no exception."
"The Benchmark LA4 yielded a change that was quickly apparent in several areas. Notably were; bass, upper midrange, treble, low-level listening, and the ability to distinguish the colorations of other components that were contributing to my overall sound."
"Acoustic guitar, piano, and harmonica among many other instruments are presented with speed, clarity, and coherency that made them sound more “present” in the room and less like a recording."
"The Benchmark LA4 is simply the most transparent, least colored, and most revealing component I have had in my system to date. I look forward to it joining my stable of reference components."
- Ken Redmond, The Audio Beatnik