He summed up: "Benchmark's LA4 is the widest-bandwidth, widest-dynamic-range, lowest-noise, lowest-distortion preamplifier I have encountered." In his listening room, KR compared the LA-4 to a cable-and couldn't hear any difference. Like other Benchmark equipment he has tested, the affordable LA4 challenged the resolution of JA's test instruments, with "superb" channel separation, "extremely low noise, and virtually no power-supply-related spuriae." Restricting his measurement to the audio band, JA found an "astonishing" S/N ratio of 105.5dB for both channels it remained extremely low across the audioband. 3 & 6 WWW)īenchmark's usual approach to design is to out-spec the competition, and so it is here. All of this is packaged in a non-huge aluminum enclosure described by AD as "tidy and evidently well laid out." Art was considerably less chipper about the KX-5 Twenty's user interface and owner's manual, for which he reserved such words as "unclear," "unneeded," "less than intuitive," and "both need work." He perked up again on hearing the Ayre's "remarkable and utterly nonclinical clarity, and its convincing, commandingly good spatial performance." Measurer-in-chief JA noted in particular the Ayre's "complete absence of power-supplyrelated" noise and its remarkably low distortion without reverting to loop negative feedback, declaring the KX-5 Twenty "superbly well engineered." In a Follow-Up, comparing the KX-5 Twenty with the similarly solid-state PS Audio BHK Signature, JCA noted the Ayre's drier sound and ability to " out a slightly deeper space," while giving the PS Audio pre the nod for controls and logistics. And its AyreLock approach to voltage regulation creates, in essence, a push-pull power supply capable of turning on a dime in response to the demand dictated by the music signal. Its active output buffer is based on Ayre's "diamond circuit" arrangement of bipolar transistors. The KX-5 Twenty line-level preamplifier enshrines almost all of the proprietary technologies that, in recent years, have put Ayre Acoustics on the map: Its Variable-Gain Transconductance (VGT) circuit adjusts volume not by throwing away varying amounts of gain but by adjusting, at its source, how much gain is created. Once he had optimized everything else in his system-cables, footers, stands, AC supply-JVS could report that the REF 6SE's "warmth and vibrancy of color, prominent midrange, and seemingly more dramatic dynamic contrasts made me want to listen more and deeper." (Vol.43 No.11 WWW) Longer-term listening indicated that the Audio Research preamplifier was sensitive to set-up issues. And unless noted, the preamplifiers listed do not have phono stages.Īn updated version of the discontinued REF 6 with changes in capacitors and wiring, the fully balanced, tubed '6SE impressed JVS, who noted that when he installed the REF 6SE in his system, his speakers "poured forth some of the most polished, transparent, and arresting sound" he'd heard from his system. Editor's Note: Apart from the Bespoke, CAT, and Shindo, all the Class A preamplifiers offer balanced inputs and outputs.
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