I recently got myself a J2 and they don't get that hot. Less heat than a push pull tube amp. I was very concerned about heat given I live in small NYC apartment. But it's totally manageable. It doesn't heat up my room. Make sure to have the amp in an open space. I can keep my hands on the amp chassis without getting bothered by heat.
Low heat alternative to FIRSTWATT J2 ?
Any Gainclone or Class D or battery power alternatives available? I like the crazy good micro dynamics and rhythmic cohesion of the J2. My speakers are 93db full range. Also interested in AMP/DAC combinations like the devialet or NAD D7050 that meet the J2 performance (those 2 mentioned don't)