Does Pass Aleph 3 heat up the room like tube amp?

Some of the amps on offer from the companies you mention offer a switch that lowers the bias and allows the amp to run a bit cooler when not in use or not being used for critical listening. Didn't know if you were aware of that or if it would make a difference, but just thought I'd mention it since I didn't see it mentioned above.

Kentchai, Plinius now makes class A/B amps that they claim sound "frighteningly close" (see their website) to their Class A amps.

I own a Plinius SA 201 and it sounds great to me. I have not been able to compare it to their Class A amps. To my ear its sound falls on the warm, musical side of the spectrum, which is what I think you are looking for with a class A amp. It runs warm but not hot.

I changed from an Aleph 3 to a 22watt SET, now that is hot. The Aleph 3 you can put your hand on for 10-15 seconds, the SET less. The SET in practice produces far more heat, it is useable, with some discomfort, in the Summer. I never kept either on all the time. The SET of course you would'nt and I agree with Truman, the Aleph 3,warms up to a good performance, quickly.

I absolutely do'nt want to reopen arguments about world resources, but personally, I find it difficult to waste electricity, sourced from fossil fuels, leaving a class A amp on all the time. Other people think differently I know, that's up to them

David,

My Diavolo 13 watt Set is probably not as hot as your Viva.
How does the ALeph 3 sound compared to the Viva?

No comparison I am afraid. I loved the Aleph 3, but the Viva outperforms it in every area, except electricity consumption. Better control of the speakers, more transparent, better base, more neutral. Mind you it should be better, it is more than twice the price, although it does include an active Pre of course