Why are most High End Amps class A

Class A is the most linear mode of operation known. But- just like with anything high performance, is the exception rather than the rule, which is to say that AB amplifiers are far more common. On top of that, there can be so many compromises elsewhere in the circuit that they may well obviate the advantage of the class A operation.

Triodes are also the most linear form of amplification known, yet the same caveats apply.

The same goes for fully balanced differential operation, circuit minimalism, etc., etc. When you combine these elements, things tend to lean more in your favor, but execution is still an issue. Cost is a different matter- Class A amps do tend to be more expensive due to the larger power transformers required.

On top of that, equipment matching will still be an issue- see
http://www.atma-sphere.com/papers/paradigm_paper2.html
for more information.

Stanwal's advice is extremely good, and there are amps amps out there that will be a whole new world of resolution compared to the Mac, but not likely for the $$$...

Gp_phan, if you can wait and save an additional $1000, and do some bargaining (at the $3000 range) on a used Pass XA30.5, then I know you will get that good Class A sound described in Audiogon. The XA30.5 works well with smaller speakers. It can do the job with some bigger 4-ohm speakers to give them 60 watts/channel, but I would be cautious. People need to do audition before buying anyway. I am not that familiar with other Class A amps beside Pass Lab as they are the lead in this niche market. Perhaps somebody else could help you with the $1000-2000 range. Unfortunately like anything else, you get what you pay for.

Consider Bi-Amping. Use a calss A tube amp for the mid-range to get warmth / big sound stage, and use solid state in the bass for impact.

Hi Scottlanterman,
"Consider Bi-Amping" interesting.. personally I was thinking about two different pre-amps, one tube based for vocal jazz and a solid state for rock