Solid State Preamp Reviews

The digital ground seems to shift weekly. While firmware and software updates over the Internet somewhat slow the constant upheaval, when you do buy something, you just know that as soon as you plunk down your cash, something new will come along.

So, especially with preamplifiers, why not produce a design based on modules that the user can swap in and out, to custom-configure the preamp to that user's current needs while leaving room for later expansion? Why pay for six inputs' worth of stuff when at present you need only two? Upgrades? New features? No problem—swap out a module. Or, if a circuit in one module malfunctions, you can send only that module back for repairs, not the whole thing.

A few issues back, in my review of the Mark Levinson No.26 and No.20 (May 1988, Vol.11 No.5), I mused on the fact that the preamplifier, being the heart of a system, had a more significant effect on sound quality in the long term than, say, the loudspeakers. It was worth spending more on a preamplifier, therefore, than on loudspeakers. Needless to say, this viewpoint was regarded by many readers as dangerously heretical. I decided, therefore, to investigate the sonic possibilities of budget-priced preamps in this issue, even the most expensive being less than one-tenth the price of the Mark Levinson.

By far the most complicated of the three preamps i review in this issue in terms of facilities offered, NAD's "Monitor Series" 1300 ($398) provides two buffered tape loops, an external processor loop (which can also be used as a third tape-recorder loop), a headphone output, a "null" switch, switchable bass equalization to extend the low-frequency range of small loudspeakers, and treble and bass controls, each with a choice of three turnover frequencies: 3kHz, 6kHz, 12kHz, and 50Hz, 125Hz, 250Hz, respectively.

In the March 2018 issue, Art Dudley admired the sound quality of Ayre Acoustics' KX-5 Twenty preamplifier, but didn't love some of its operational aspects. I've staged this Follow-Up as a putative face-off between the Ayre and my current reference preamplifier, the PS Audio BHK Signature, which I reviewed in the June 2017 issue.

Each equipment report in Stereophile focuses on a single audio component. When listening to a component for review, I leave unchanged all other components in my audio system. Other Stereophile reviewers experiment with different interconnects, speaker cables, power cords, or stands. As I found while reviewing Bryston's BP-17³ (Cubed) preamplifier, being flexible has its rewards.

Description
My first lesson in flexibility was learning what Bryston means by "Cubed" (footnote 1). Jim Tanner, Bryston's VP of sales and marketing, explained that all their Cubed models employ an array of 12 active devices for the first 6dB of gain. Developed by the late Dr. Ioan Alexandru Salomie, this array acts as "a super-linear" input buffer to filter out audio- and radio-frequency noise, particularly anomalies that originate in the power line, reducing the overall noise and distortion to less than 0.001%.

Classé Audio's flagship preamplifier, the Six, has enjoyed a five-year life span—quite long for an audiophile component. Company president Glen Grue reports that the Six's sales have continued to improve during that time. How to explain this solid-state preamp's continued success in competition with today's newer, remote-controlled, line-stage preamplifiers?

One never knows, do one? Within the past year, I've had six preamplifiers in my system for critical evaluation, reviewing four of them and using another two as references. I was getting pretty tired of listening for sonic differences among preamps, and I told JA that I'd prefer my next reviewing assignment to be something different, like a speaker or a power amp. He agreed, but said he'd first like me to review just one more preamp, the Perfectionist Audio CPR/TIPS, which had been waiting patiently in the review queue in Santa Fe. Well, one more wouldn't hurt. Sounded kind of interesting, anyway: a preamp with a battery-operated power supply!