Tube Power Amp Reviews

The MC275 was not without weaknesses. In general, very low frequencies tended to sound a little more like bass tones than like notes played on an instrument. The big bass drum at the beginning of "Nuages," on the James Carter CD, didn't have quite the oomph in the attack, or quite the persistence in the decay, that it should. On 88 Basie Street, the notes from Cleveland Eaton's bass were distinct, but the plucking was too soft. Similarly, on Dolphy's Out to Lunch, Richard Davis' bass, though once again its notes were very clear, lacked the wood that this album, and especially this reissue, very much conveys. When musical passages got dense, whether on the Radiohead album or in Górecki's Symphony 3, in the recording by David Zinman and the London Sinfonietta (CD, Elektra Nonesuch 79282-2), the double basses got a bit muddy, though only a bit—the tones did still come through, something that can't be said for many amps in this price range. At the climaxes of the crescendos in the Mahler and Górecki discs, the MC275 didn't open up with the full dynamics that a more powerful amp might have unleashed. But it did open up part of the way—the sound got not just louder but bigger, and more so than I would have expected from a 75Wpc amp—but at no point did the soundstage collapse or the horns sound more than just a teeny bit strained. The MC275 dealt with its limitations gracefully, which is the best way to do it.

Here, though, I should stress that some of the amp's shortcomings in the deepest bass octave may have stemmed, in part, from my system. The Revel Ultima Studio2 is nominally a 6 ohm speaker, which raised the same question it would with any tube amp: Should I hook up the Studio2s to the amp's 4- or 8-ohm taps? I opted initially for 4 ohms because John Atkinson's measurements of these speakers, accompanying Kal Rubinson's review of them in the March 2008 Stereophile, noted an impedance dip in the midrange. Because the MC275, like most tube amps, was likely to perform at its best in the midrange, I figured I should aim for the closest impedance match in that region. And, as I've noted, the MC275's midrange, along with much else, sounded wonderful. When I switched to the 8-ohm taps, the soundstage wasn't quite so deep, violins and voices weren't quite so warm, orchestras weren't quite so dynamically coherent—but the bass was a bit tighter. All the bass problems mentioned in the paragraph above were still there, but not so prominently; things were a bit tighter, a bit woodier, a bit pluckier, a bit oomphier.

I hooked the Revels back up to the 4-ohm taps and left them there for most of my listening, but your preferences may dictate a different choice. More to the point, if your speakers are rated at 4 or 8 ohms—not just nominally, but consistently across the audioband—you may be able to enjoy the best of what the MC275 has to offer in the highs, mids, and lows, all at once.

But even then, I think, the MC275's performance would fall short of the best. I didn't fully appreciate this until I switched back to the Krell FBI integrated—that is, until I removed the McIntosh from the system and resumed using the Krell in its full operating mode, as both preamp and power amp. Suddenly, I heard not only tighter and deeper bass, but also more extended highs, more musical detail, more subtle gradations in dynamics—more of a sense that people were playing the instruments and singing. On John Scofield's Quiet (CD, Verve 314 533185-2), his fingerwork on acoustic guitar was more intricate, practically visible. On the Maria Schneider Jazz Orchestra's Sky Blue (CD, ArtistShare AS0065), I could better hear the bloom of overtones and the texture of each instrument: the breath of the flute, the brass of a horn, the hammers on the piano.

Two things are worth noting about this comparison. First, the MC275 costs $4500, while the Krell FPB-300cx (the circuitry of which is incorporated into the power-amp section of the FBI integrated amp) retailed at $8500 when it came out a few years ago. It's not surprising, then, that the Krell might have a few things the McIntosh doesn't. Second, even so, I had to A/B the units to hear the Krell's advantages directly. The differences, for the most part, were not enormous, and a few were quite subtle; the McIntosh fared a bit better in terms of soundstage depth and intertransient silence.

Finally, just to make sure that the MC275's shortfalls weren't the result of some sort of mismatch with the Krell, I plugged the MC275 back into my system, this time connecting it to McIntosh's C2300 tube preamp. I didn't listen long enough to formulate a review, or even a very deep sense, of the C2300. Suffice it to say here that what I heard didn't alter my assessment of the MC275's strengths and weaknesses. With the C2300 driving the MC275, the sound was a bit too plummy—a bit too close, for my taste, to the "old tube sound" that the MC275-Krell combo transcended.

Conclusion
Carefully set up and matched with other components, the McIntosh MC275 is a very good, very well-balanced amp that goes higher, lower, louder, and softer, with more texture and detail, than you might expect from a "modified classic"—or, for that matter, from any tube amp costing less than $5000. It certainly did more of all that than I was expecting. By any standard, it made listening to all kinds of music a pleasure. I could happily live with it.