Solid State Preamp Reviews

Before starting this review of Rotel's Michi P5, the 60-year-old, Japan-based audio company's recent preamplifier design, I thought it appropriate to consider "What is an audio preamplifier? What should it do?" There are plenty of opinions to be found at stereophile.com:

"What a preamp ought to do, apart from changing volume and switching sources, is as little as possible," wrote Stereophile Editor Jim Austin in his 2017 review of the PS Audio BHK Signature preamplifier.

I thought I knew what a preamp could do. But when the Dan D'Agostino Master Audio Systems Momentum HD preamplifier ($40,000) arrived for review, all my expectations flew out the window.

For those who listen with their ears and not their brain, perfectionist hi-fi offers many surprises.

A friend called me up a few weeks ago and asked if the DAC we both own had received an automatic firmware update he hadn't heard about; something had changed, it wasn't good, and he couldn't figure out what it was. His system's sound was suddenly pale and unfocused.

There had been no firmware update.

Like most serious pursuers of the audio hobby, I've known about J E Sugden & Co. Ltd. for years. For many of those years, though, it was easy to forget about them, and I mostly did—until, quite recently, Sugden gear began popping up at audio shows, including the 2016 Rocky Mountain Audio Fest. In his report on that show, Herb Reichert described the midrange of Sugden's A21SE Signature, a pure class-A integrated amplifier, driving DeVore Fidelity speakers, as "shroom-like" and contrasted the sound with what he called class-D's "fake cocaine." That got my attention.

In the early 1990s, the Compact Disc was all the rage, and vinyl records were being executed en masse. Thirty years later, and oh, how our tables have turned. Mint first pressings of tenor saxophonist Hank Mobley's 1957 album Hank Mobley (Blue Note BLP 1568), which once could be had for $40, now bring upward of $8000. Each. Vinyl continues to enjoy a global resurgence of popularity, while CD sales have plummeted to all-time lows.

What happened? Apparently, yesterday's pops and ticks are today's "warmth," Record Store Day exclusives, and skyrocketing vinyl values. All things old . . .

Sometimes, I feel I'm two people. One, a card-carrying audiophile, is always looking for ways to optimize his enjoyment of multichannel music recordings, a purist pursuit that begins with file playback and leads to DACs, amps, and speakers, while eschewing anything that can complicate or compromise the sound. Thus, while his main system may seem elaborate to outsiders, to him it seems streamlined: NAS>player>DAC>preamp>power amps>speakers. In fact, it's possible to combine the NAS and player in a single device, if that device's CPU and RAM are capable of doing all the tasks—but these product categories continue to evolve so quickly that he prefers to keep them discrete.

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%.