"Benchmark's LA4 is the widest-bandwidth, widest-dynamic-range, lowest-noise, lowest-distortion preamplifier I have encountered."
- John Atkinson
"I measured the Benchmark LA4's performance with my Audio Precision SYS2722 system (see the January 2008 "As We See It")."
"The preamplifier's frequency response in both balanced and unbalanced modes was flat from 10Hz to 200kHz both into the high 100k ohm load and into 600 ohms was taken with the LA4's volume control at its maximum setting; both the response and the superb channel matching were identical at lower settings of the control."
"The gain for the balanced inputs to the balanced output with the volume control set to "+15" was exactly 15dB, and reducing the control to "0.0" resulted in a gain of 0dB—ie, the output voltage was the same as the input voltage."
"The LA4's balanced input impedance was both usefully high and higher than the specified >50k ohms, measuring 80k ohms (40k ohms per phase) at 20Hz and 1kHz and still 75k ohms at 20kHz."
"The balanced output impedance was a low 61.5 ohms, the unbalanced impedance 201 ohms, both values consistent across the audio band."
"Channel separation was simply superb, at >140dB, R–L, and >132dB, R–L, below 2kHz, respectively decreasing to 130dB and 112dB at 20kHz."
"The superb separation measurement is a testament to excellent circuit-board layout, something I have commented on before with Benchmark D/A processors."
"From balanced inputs to balanced output, the Benchmark preamp offered extremely low noise, with virtually no power-supply–related spuriae in its output."
"The LA4's balanced output doesn't clip (ie, when the THD+N reaches 1%) until a very high 24V."
"I looked at the spectrum of the distortion at a similarly high output level; while the second and third harmonics can be seen, these are still at astonishingly low levels: each harmonic is at or below –120dB (0.0001%) and is close to the residual level of these harmonics in my Audio Precision SYS2722's signal generator."
"Tested for intermodulation distortion in balanced mode with an equal mix of 19 and 20kHz tones at peak level of 5V, the second-order difference product at 1kHz was effectively absent, and the higher-order products all lay at or below –114dB."
"Benchmark's LA4 is the widest-bandwidth, widest-dynamic-range, lowest-noise, lowest-distortion preamplifier I have encountered."
- John Atkinson, Stereophile Magazine
The above is just a brief summary of John Atkinson's independent lab tests. Please follow the link below to read his entire test report which includes 9 high-resolution test plots (including the two shown above).
"Merriam-Webster defines a benchmark as "something that serves as a standard by which others may be measured or judged." This is what the AHB2s has become for me."
"A pair of AHB2s are now part of my dedicated summertime amplification for my Sound Lab 545PX loudspeakers."
- Don Shaulis, The Stereo Times
"I was led to Benchmark Media Systems through recommendations from Roger West, the designer of Sound Lab speakers. Praise from a local Sound Lab dealer and a local Sound Lab owner effectively twisted my arm to the point where I yielded to temptation to try the amplifiers ..."
"The Class-H Benchmarks give me what I wanted from Class-D amplifiers, but with the musical engagement, I found lacking in Class-D. There is the added benefit of a company that has been in business for over 36 years and has a depth of products, and offers an extended warranty."
"The highest compliment I can pay a piece of audio equipment is that it has found a home in my system. A pair of AHB2s are now part of my dedicated summertime amplification for my Sound Lab 545PX loudspeakers."
"The Benchmark performance continues to engage me, and the company gives me confidence in long-term support."
- Don Shaulis, Stereo Times
"I love, I love, I love my Benchmark AHB2 power amps!"
- Theo Nicolakis, Audioholics Online A/V Magazine
Theo uses a pair of AHB2 power amps in bridged mono (480 W into 6 Ohms) to drive a pair of Revel Ultima Salon2 loudspeakers ($20,000/pair). This is his reference amplifier-speaker combination.
Find out why Theo loves his AHB2 power amplifiers: