Well, I've traded my CAT JL2s for Atma-sphere M-60s. Both are fantastic amps, but on my Merlins, which are OTL friendly, the OTLs are pure magic, I clearly prefer them in almost every way, though the nod has to go to the CAT on bass IMHO - not that the M-60s are not perfectly satisfactory, but those huge transformers on the CAT are there for a reason. I suspect with other speakers the CATs would have the advantage - they can drive most anything, but if your speakers are OTL friendly I suspect nothing will sound better than an Atma-sphere amp, and proabably the Joule OTLs as well.