Audio Research 300.2, Classé CA-M400, McIntosh MC 501 Power Amplifiers

Why are amplifiers so important?

I think you can get a reasonable idea about some aspects of these amplifiers from the graphs, but it isn’t so easy to say which is “best.” To do that, you have to know your system, your preferences, and your needs. At least if we’re in the tuning mindset.

That’s fine, and I stand by it, but after another month of listening, I sensed that there is another dimension to the question of why experienced audiophiles think of amplifiers as so important.

Having taken my listening notes and written the first part of this review, I had the chance to listen to some music without thinking too much about it. The great thing about this phase of the process is that you can look down after awhile and see which amplifier is connected the most. As I noticed which amp got the most playing time, I was struck by the fact that I really enjoyed listening to it much more than the other amps. I think part of that is because it fit nicely with the strengths and weaknesses of my system. But I don’t think that gets to another important matter.

An age-old concept is still at the leading edge of amplifier design and, under the right conditions, can make a big difference in how musically involving a really good system can be. That concept is transparency.

I am well aware that transparency has a bad name in some circles. Certainly we have all heard what might be called fake transparency—as an example, the elevation of the treble range to make things sound clear. Yet certainly clarity is what we’re talking about when we say transparency, or in other words the sense that the proverbial veil has been lifted between the listener and the source. From time spent with these four amplifiers I would say that modern amplifier design has allowed a great step forward in real transparency. That is to say, the better amplifiers today sound clearer than others, while oftentimes showing a complete lack of the artifacts we associate with artificial transparency.

A critical sub-component of transparency is what has been called continuousness. Continuousness puzzles many, as well, though more from a certain vagueness about what it means. It perhaps does some damage to the full idea, but by continuousness I mean a lack of grain coupled with a sense of purity and wholeness for each note. If transparency most often is noticed at, say, the orchestral level, continuousness is an attempt to describe transparency down at the instrumental level. How does the bow sound on the string? Does it sound real?

What unites these two related ideas in this case is that both transparency and continuousness seem to stem from the dynamic behavior of each amplifier. I got an insight into this while visiting HP for a listen to the ASR Emitter II. The ASR in Harry’s system renders soundstage depth and width more clearly than on any other system I’ve heard. If you think about it for a moment, the cues that signal that a reflection is coming from, say, the right rear or the center rear of the stage are relatively low level in comparison with the initial sound from the orchestra. So, rendering them accurately requires handling very small signals well. It seems consistent with my experience that doing this isn’t so easy, at least in big amplifiers.

Having observed this soundstaging accuracy in HP’s system, in hindsight I’m not surprised that I also observed that the ASR sounded very clear, and yet it has a timbre that makes tube aficionados happy. The key thing is that when you get microdynamic behavior right, you get improvements without tradeoffs.

I noticed a version of this with the CA-M400 as well. It reaches back into the hall quite well and presents each instrument clearly, yet has a very natural, maybe even warmish, tonal balance. The McIntosh has a similar tonal balance, but doesn’t seem to reach into the hall as vividly. The Audio Research can reach back into the hall pretty well, though I always felt this ability varied with the instruments being played. Basses, cellos, and horns were very well portrayed, but violin at times, and guitar more often, sounded more forward.

I noticed that the amps I had under test had different performance on bigger transients, with similar side effects or lack thereof. The McIntosh seemed slightly sluggish on big orchestral dynamics, though it never sounded harsh or unpleasant. The Classé, in contrast, did a good job of sounding punchy while at the same time maintaining a sense of control over the leading edges of transients. By controlling the leading edge of transients, the Classé avoids sounding hashy, but at the same time lets the instruments come through quite clearly. The Audio Research provides an instructive comparison, in that it puts a little extra emphasis on each transient. This nicely spotlights each instrument, and sounds even more lively than the Classé, but at times this transient-handling also creates a richness and some fog over the whole presentation. This can sound very nice, but it isn’t what I would describe as ideal dynamic behavior (again, I should note that warm-up time makes a big difference with the ARC design).

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