Class A amplifiers - which are considered the best

If you can find one in good condition...then I would say the original Krell KSA50.
Hard to think of another Pure Class A amp that is significantly better than Dan's original design, just IMHO.

If we included a classic class A amp in the 80's/90's..

***** THRESHOLD 4000 ***** 200 WATTS CLASS A

I also have Mark Levinson No20's bridged. They output 400W into 8 Ohms, 800 Watts into 4 Ohms or 1,250 Watts into 2 Ohms. At 2 Ohms that is continuous sine wave power. These to sound magnificent on Infinity IRS V's.

Mark Levinson 20.6 amps. Absolutely one of the best ever made and will blow away most of the amps made today. When going away from Mark Levinson the person, I guess the new company had to move forward with different (non Mark Levinson designs). But, what a great amp.

enjoy

Levinson ML-2,
Levinson no. 20.6
Sumo Nine
Threshold SA/1