"Benchmark'sLA4is 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."
Input and Output Impedance
"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).
LA4 - Receives Stereophile's Highest "Class A" Rating for Preamplifiers
"Benchmark's usual approach to design is to out-spec the competition, and so it is here. Like other Benchmark equipment he has tested, the affordable LA4 challenged the resolution of John Atkinson's test instruments, with'superb'channel separation,'extremely low noise, and virtually no power-supply-related spuriae.'"
"Benchmark's LA4 is the widest-bandwidth, widest-dynamic-range, lowest-noise, lowest-distortion preamplifier I have encountered."- John Atkinson
"In his listening room, Kalman Rubinson compared the LA4 to a cable—and couldn't hear any difference. He concludes,'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.'"
"The DAC3 B is a stripped- down, lower-priced version of the DAC3 HGC, which omits the headphone amplifier, balanced and unbalanced analog inputs, volume, mute, and polarity controls."- Stereophile
"The DAC3 was all about depths, in several respects...I heard deeper into the music."
"All I can say is Wow!"
- John Atkinson
"In a Follow-Up, JCA 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."