Why are most High End Amps class A

The wine analogy that Kirkus used might be the way to go here, but with wine the you can try many types easily and see what you like and have a collection of Cabernet, Pinot, Chardonnay, etc.

But with Hi-Fi, you can't collect to the same degree, and you cannot sample to the same degree. So I think for many people we rely on the audio equipment equivalent of the master sommelier, like reviews from Stereophile as stated above or sound engineers with a lot of experience and people who have been into it for a long time. The expense of audio, and the rate of audio collection, generate a reliance on expert advice in this kind of situation.

So what is the advice for the guy who started this thread, he likes his McIntosh gear. What would be an interesting flavor change, would a Plinius SA100 mkIII be an interesting taste choice? Better is pretty subjective, but how would a class A amp with his McIntosh pre be different?

My days of sampling different amplifier classes are over. I don't want to knock anybody thus won't mention various equipment brands. Yet I can tell you that through the years I listen to equipment from a lot of major brands. None of them remotely come close to what the real Class A amplifier can do. As to those who have other priorities to spend money at this moment, it does not cost anything to just go listen to these equipment. When you see that much a difference, perspective and priority can develop different meanings. Because of the type of discussions and reports people have about the XA.5 series and that I own and know how Pass Lab XA60.5 sounds, it's obvious as to my recommendation. I am just too in awe of the difference to sit still on this.

Now from a different angle, the more expensive a purchase, the longer it better stays with me. Even $100 is a good amount of money, needless to say $1000 or $2000 that Gp_phan is thinking about. I am not about to spend $1000 when realizing that a year from now I would loose so much just because I really want something else instead. But that's just me.

Spatine, I share your respect for Nelson Pass and his products, even though they're not my cup of tea. But since his amps are generally single-ended designs with a high output impedance, I would say that the "class-A-ness" isn't necessarily the main source of their sonic characteristics, and the advantages/disadvantages of these aspects of his designs require separate consideration.

That's the main reason why I chose the Levinson ML-2/ML-3 for comparison . . . where the circuit designs are much more similar, whereby the Class A/Class AB distinction is THE big difference.

If anyone is interested there is a master class lecture by Douglas Self on audio amplifier design. His talk is interesting for its lengthy discussion of distortion mechanisms and the new Cambridge 840 XD design which he mentions briefly (a kind of offset bias to bring the crossover region to where it is less obtrusive).

He did not mention active speaker designs with limited bandwidth as a solution to the many necessary compromises required to achieve wide bandwidth in conventional approach- but he talks about nearly everything else.

I'll second the recommendation on Self's work . . . he also has a couple of excellent books on the subject. I don't necessarily agree with all of his approaches and conclusions, but everything he presents he does with wonderful concise logic, and thoroughly cites all his sources - which seems to be rare in the audio field these days. He's definately one of the modern masters of audio amplifier design, and a delight to read as well.