Audio Research M300 monoblock power amplifier Page 3

I won't pretend for a moment that reproducing disc warps is a good thing; it increases LF distortion from the speakers and wastes amplifier power that is better directed toward reproducing program material. But the place to control that garbage is in the cartridge/tonearm, through the choice of a sensible, well-damped LF system resonance, and in the preamp phono stage, by adherence to the IEC/RIAA's standard playback flatten-out below 50Hz. Even the subsonic filters found in some preamps tend to thin out the low end. If the arm/cartridge LF resonance is effectively damped, so the peak is of negligible amplitude (as is the case with the Ortofon/Versa Dynamics combination), subsonic response is of no consequence except with very badly (or abruptly, as with pinch warps) undulating discs.In other areas, the M300 is as close to being absolutely neutral as any amplifier I know of, and perhaps as close as it is possible to get. It is, perhaps, a very tiny bit forward, but I couldn't be sure of that: when you get this close to dead center there is really no way of telling precisely where that center is. But this amplifier is definitely laid-back, crisp, rich, warm, or sweet. It is, in fact, hardly there at all. The sound, from top to bottom, is completely coherent, with no audible changes in texture from the deepest bass to the extreme treble. Highs are completely grainless, with an effortlessness and openness that must be heard to be believed. They are, simply, musically right. Talk about air! These sound as if they just keep going out toward the radio band, even though the amp has, in fact, rather less HF extension than some solid-state units.Soundstage presentation, too, is superb, with the breadth and spaciousness I have come to take for granted from true dual-mono power amps. (Harry Pearson, reviewing the M300 in The Abso!ute Sound, claimed that it compressed stage width. I emphatically disagree.) Its front-to-back depth is not as great as I have heard from some power amps (notably the conrad-johnson Premier One), but is, I believe, as accurate as one can get. I base that last statement on having listened to a number of recordings I made myself, which allow me to compare the depth I hear with the mike/instrument distances that actually existed when the recordings were made. I won't pretend that exaggerated depth doesn't sound nice, but then we're all interested in accuracy, right?

Conclusions: As you may have gathered, I was immensely impressed with this amplifier. After having lived with a pair of them for a week, and sampled countless (well, uncounted anyway) old and new recordings on it, I still cannot find anything to criticize about its sound, although I'm working on it. But then, I came to the M300 with, perhaps, less prejudice than I have approached other power amps with recently, because prior to my first listen I had been away from home for two weeks, and thus did not go straight from listening to my "reference amps," the Threshold SA-1s, to the new ones. Then, after listening to the M300s for about a week, I went back to the Thresholds.

I believe that, after two years with the Thresholds, the time has finally come to switch allegiances, although I will have to make some changes in that part of my monthly budget now assigned to electric bills. Of course, I probably couldn't distinguish between these amps on the basis of blind A/B tests in an unfamiliar system, just as I found it almost impossible to distinguish ARC's SP9 and SP-11 preamps under those conditions. But in this case, I don't think Bill Johnson will insist that I try.Since a pair of M300s costs more than any other stereo amp (or pair) I have ever encountered, I cannot really compare them with "the competition." I can, however, compare them with some other costly units I've heard in recent months. Note, though, that these comparisons pertain to operation with my Sound Lab speakers, which have neither the absurdly high current requirements of some others (notably the big ribbon systems) nor the rounded-off high end of most dynamic systems.Overall neutrality of the M300 is comparable to that of the Threshold SA-1s, although the ARC is a little more forward and "alive" by comparison. The Krell KSA-100 is a trifle warm and rich, while the Mirror Image is somewhat laid-back, and the original Rowland Research Model Seven a bit more so. On bass performance, the M300s are very similar in heft to the Krell and the Threshold, but with a little less impact and tautness. The Mirror Image 1.1S is slightly leaner and tighter than any of these three, the Rowland 7 just a trifle more so. Of the three, the M300 has the least sonic texturing, being about as liquidly transparent as any amp I have heard. It is followed very closely here by the Krell, Mirror Image, and Rowlands, while the Threshold, by comparison, is a bit dry.

At the high end, the M300 just doesn't warrant comment; it is, for all intents and purposes, perfect in that area. Of the others, the Krell, Rowland, and Mirror Image are all gorgeously sweet and open at the top, but by comparison with the M300, they sound more as if they have an extremely fine grain up there than being completely texture-free. (Until now, they had the best top of any amps I had heard.)

Soundstaging: The Krell, Rowland, and M300 are comparable in breadth and spaciousness, but the M300s seem to deliver depth better—not by having more of it, but by making front/back perspectives more readily audible. No other amplifier(s) I have ever auditioned can produce the M300s' holographic imaging of three-dimensional instruments in space. They are, simply, there, right before your very ears! I think it is long past time, though, that we expressed here as a generality something we have all been observing for the past few years: namely, that the widest, most natural soundstaging is only attainable through the use of completely separate power supplies.All of the other amplifiers I mentioned cost substantially less than a pair of M300s. Is it really worth the difference? I would love to be able to say "No way!," but since I can't think of another amplifier that sounds better in so many areas, or even as good, regardless of cost, I can hardly argue with that cost. OK, Bill, now how about a 100Wpc stereo version of the M300 that sounds just as good at lower levels but costs a mere $3000?—J. Gordon Holt

Audio Research
3900 Annapolis Lane North
Plymouth, MN 55447-5447
(763) 577-9700