"The LA4’s relay-managed volume control has 256 steps of adjustment of 0.5dB each, and is fully balanced -- each channel has its own dedicated attenuator. Each increment of volume adjustment produces a satisfying click from the 40 relays inside. Other circuit features include precision-timed relay closures, gold contact points in the relays, and metal-film resistors."
"The LA4 has an expansive specified frequency response of 0.1Hz-500kHz, -3dB. Other impressive specs include a signal/noise ratio of >137dB (A-weighted) and total harmonic distortion (THD) of <-125dB (<0.00006%). Benchmark has also tested the LA4 for “immunity to radiated and conducted radio frequency interference.”"
"Benchmark Media Systems’ LA4 preamplifier presented an utterly realistic reproduction of what was contained on each recording I played through it -- and weak recordings stood out more than usual. The LA4’s clean, analytical abilities are unmatched by any similarly priced preamplifier I know of. The LA4’s touchscreen brings it up to date with current user interfaces, and permits functions, such as balance control and muting at the device."
"Operation of the user interface is intuitive -- I found the LA4’s many features easy to find and adjust."
"The LA4 was designed from the ground up as an ultra-low-noise, ultra-low-distortion mate for the AHB2 power amplifier, which my brother Hans reviewed on SoundStage! Access in June 2015. Our measurements of the AHB2 confirmed that it had the lowest noise and distortion of any power amp we’ve ever measured. Benchmark claims that the LA4 (and HPA4) “may be the only preamplifiers or line amplifiers that [exceed] the signal-to-noise ratio of the ultra-quiet AHB2.” If so, the LA4 may be closer to the elusive ideal of a “straight wire with gain” than almost any other preamplifier on the market at any price."
"If you want a preamp that editorializes, look elsewhere."
"If, like me, you value a high-resolution, totally neutral musical performance, add a Benchmark LA4 to your system, particularly if you already own a Benchmark DAC."
- Erich Wetzel, SoundStage! Hi-Fi
"This little unit will change the way you look and listen to amplifiers."
"My first taste of this remarkable new amplifier came earlier this year in April at Chicago's AXPONA where I discovered it driving a newly redesigned Studio Electric Pasadena loudspeaker, also bearing the Benchmark trademark. Now called the SMS1, the Pasadena's crossover had been reworked by Benchmark, upgraded with very low tolerance components, and the new look, more in line with the look of the rest of the Benchmark product line up, had been adopted."
"The subsequent sound in this room was one of the most musically engaging I encountered at this year's event, a remarkable result considering its modest overall system price of just over $7000, sans source."
- Greg Weaver, EnjoythMusic.com
Jim Austin wrote, "The DAC3 was all about depths, in several respects . . . I heard deeper into the music."
The concise conclusion to John Atkinson's Measurements sidebar: "All I can say is 'Wow!'"
In a Follow-Up, Jim Austin wrote of using the Benchmark processor with the same company's AHB2 power amp—a combination of high source output voltage and modest amplifier gain that he describes as "optimal for minimizing noise and distortion"—and reported hearing "richer and more interesting" reproduction of very subtle details.
- Stereophile Magazine
"Class A+" is Stereophile's highest award for Digital Processors
"Benchmark's LA4 is the widest-bandwidth, widest-dynamic-range, lowest-noise, lowest-distortion preamplifier I have encountered."
- John Atkinson, Stereophile
"The LA4 is probably the most transparent and revealing audio component I've ever used. It does not seem to leave any fingerprints on the sound."
- Kalman Rubinson, Stereophile
"Class A" is Stereophile's highest award for preamplifiers.