Most NEUTRAL class A mono's

Original Sonic Impact T-amp.

Sanders Sounds mono's seem to be very neutral. I am using the ESL Monoblocks for Soundlab M1's and they have enormous power and finess. Very under rated amps - worth a listen. Roger has the Kilowatt Monoblock's for non-ESL speakers.

Sorry, I meant to add that the Sanders are not class A but seem to be in that league without any of the heat problems. I was looking for a high power class A single ended amp but the cost can be over the top and they use hugh amount of power and run hot etc. I love class A but so far I am very impressed with the sound of the Sanders. They idle at 7w but can peak at over 2000w

Surely Atma-Sphere MA 2s must rank?

Gryphon Mirage and Colosseum amps. The Antileon Signature Mono's are also quite good, in a different league vs the stereo.