Halcro Logic MC20 power amplifier Jim Austin, June 2009

Jim Austin wrote about the Halcro Logic MC20 in June 2009 (Vol.32 No.6):

The $4995 Halcro Logic MC20 is a lesson in stereotypes defied. It demonstrated that pretty much everything I ever assumed I knew about digital amplification is wrong.

My tastes as an audiophile lean toward the simple. The more direct and simple the connection between the original musical source and my eardrums, the happier I tend to be. I love the simplicity and elegance of analog transducers and step-up transformers converting mechanical vibrations into moving electrons in a way that I find direct and easy to comprehend: from music to electricity. I prefer fewer gain stages, generally, and few-way speakers with minimalist crossovers.

I'm no zealot—I enjoy digital, and I like a little bass and treble to go with my midrange, so I don't go in for low-powered single-ended-triode tube amps and single-driver speakers. But my biases, if not necessarily the products I own, tend toward the less complicated end of the audio-tech spectrum. This is an ideological as much as an aural preference, and thus subject to revision as I hear new gear. Still, you need to know: Going into this review, I preferred my music straight up, sans long ingredient lists and paper umbrellas.

Halcro Logic's MC20, the two-channel version of a series that also comes in multichannel varieties for home-theater enthusiasts, is a switching amplifier—a relatively new technology that no doubt has a very long parts list. And John Atkinson's measurements of it looked awfully scary, with a lot of ultra-high-frequency noise that alarmed me. My response is irrational, I know: the noise is way above the range of human hearing, and above what any loudspeaker I know of can produce. Still, the noise isn't a pleasant prospect. Add to that the MC20's astonishingly resonant case, which Art Dudley pointed out in his April 2006 review—tap it and you feel you could almost break a wineglass if you excited it at just the right frequency—and let's just say that I did not expect the MC20 to be to my taste.

But despite its parts count, measured HF noise, and very resonant case, the MC20 had a simple sound that was very easy on my ears. From the beginning of my extended audition—I kept the MC20 for months, using it with several different sources and two pairs of loudspeakers—I expected to hear something I didn't like. Like-minded audio friends and colleagues—my friend Bryan, who listens to tubes and vinyl almost exclusively, and a visiting speaker manufacturer who shares my taste for simple technology—encouraged me in my bias as I searched for a telltale sterility or an absence of emotional immediacy. I never found either.

Art Dudley said that the Halcro sounded like no other amplifier he'd ever heard. My less experienced ears detected no such radical departure from my own past experience—only from my expectations. But it was almost as if Halcro had set out to confound the expectations they knew such a product would engender. First, imagine the fatiguing, bright sound of ringing casework. Or imagine what John Atkinson's graph of the MC20's small-signal 10kHz squarewave into 8 ohms might sound like were the overlying mess in the audible range (see fig.1 of the original review).

Then imagine the precise, subjective opposite—not a hole where the high frequencies ought to be, but a sound that lacks even a trace of glare or HF electronic hash. That's what the Halcro Logic MC20 sounded like. All the HF information was there, but it was always easy to listen to, never fatiguing. There was a touch of darkness and a dryness that I, who can't tolerate a bright, "high-tech" sound, found very pleasing. It was almost as if, somehow, the MC20 very slightly accentuated the somewhat dry acoustic of my listening room. It was almost as if Halcro Logic had set out to confound the biases of simpleminded audiophiles—audiophiles like me.—Jim Austin

US distributor: Halcro Audio USA
871 Grier Drive, Suite B-1
Las Vegas, NV 89119
(702) 270-9307