How hot is hot when moving from class a/b to to a or tubes?

@decooney 

i kept the hot question vague for the reason you describe - want to get a gauge on how others articulate it. My main concerns were: potential burns to the kids (probably their friends. Thanks @jonwolfpell for the cage comment), how much it will heat my already hot home, anyone speaking about shutdown modes from over heating (there are few Texas folks running them in the summer, the UK won’t be hitting those temperatures), hopefully getting some insight on what experienced owners would do if they were starting out again. 

I’ve never owned tubes so I have too many unknowns. 
My next stage will to start home demos and take it from there. 

A lot of the tube amplifiers mentioned in this thread are much more power than you need.  2 wpc will be enough unless you like concert volumes.  A 2 wpc tube amp will be almost no heat.

Also, my comments above are made without air conditioning.  I live on the california coast and don't have air conditioning.

Jerry

@carlsbad i hear you there. I will be looking at single digit wpc. 
very excited for the next steps. 

@mpoll1 My main concerns were: potential burns to the kids (probably their friends.

Two added points of information have surfaced here. And, if you plan to keep your nice L509x amp and rotate in a tube amp once in a while, going a new/lower power direction will be key for less heat and you can also look at integrated tube amps with an enclosure. Do you want to stare at tubes or keep them enclosed, separates or integrated all-in-one unit?

While some will push for the fleawatt single-ended-triode tube amps down in the 2-3 watt range, there are also some very nice EL84 based tube amps in the 20w range that can be nice too. Thinking if you want something [enclosed], we can also make a plug for this one, makes it nice for those starting out with tubes. Here is another to give ideas. Some used ones out there right now too. Another option, fwiw.

@jasonbourne52 

You are quite right about TRUE Class A. It does run hottest on no/low signals.

Some here have mentioned modern Krells, by which I mean post around 1990.  These do not run particularly hot on no/low signals.  How can this be?  it is because they are not TRUE Class A, whatever Krell may claim.  They run in Class B and have so-called anticipator circuits which sense an increased signal coming in and re-bias the amp to Class A and allow it to morph back to Class B when the volume has died down.

I have never discovered any scientific basis for the claim that this re-biasing can occur so quickly after detecting the increased signal that it can power the sound of that signal.  It seems impossible since the cable runs in the amp are relatively short and the signal is travelling in them at close to the speed of light.  A myth put about by Krell so they could play in Green Park while still claiming to produce Class A amps.  Yes they will exhibit patents but anyone can get a patent.  The issue is: is  the move to Class A completed before the detected incoming signal is amplified?  The patent makes no claim that it is.

No guys.  A TRUE PURE Class A amp like my pair of late 1980s Krell KRS200s, uprated by Krell to 400w per channel runs HOT.  And as Jason says, there aren't many of them.