How hot is pure Class A solid state vs. SET?

It looks like the A318B uses a pair of 6C33C's, which is an extremely hot-running tube. Its filaments alone consume in the rough vicinity of 40 watts per tube, assuming both filaments in each tube are used. So your EL84-based amp figures to be considerably more efficient.

Also, just to be sure the light bulb reference is clear, nothing on the Pass amp will come close to being as hot as the surface of the bulbs, since in the case of the amp the heat will be radiated from a much larger total surface area (the Aleph 30 manual indicates that the heat sink temperature will be between 120 and 130 degF). But the total amount of heat radiated into the room by the amp will be about the same as if two 100W incandescent bulbs were positioned at the same location (slightly more than that, actually, as my understanding is that an incandescent bulb will convert about 10% of the power going into it into light, the other 90% being converted into heat).

Best regards,
-- Al

The First Law of Thermodynamics -- Conservation of Energy (as Al's practical example implies): All the energy you draw from the wall -- as consumption by anything in the chain, including the Romex inside your walls (see below)-- is going to end up as heat and radiation, save initially for the < 2 watts of acoustic power in the room on average, a fraction of which you will actually end up perceiving.

The Second Law of Thermodynamics -- All energy differences [gradients] tend to equilibriate over time in so-called "closed systems"; from that we deduce the concept of Entropy, and the gradual loss of the ability to do "work" in these isolated systems. A good deal of the acoustic energy that makes it into your ears ALSO ends up as entropy, heating up your skull just a bit: you are a space heater, too, and not just on account of your metabolism.

Here in my home town is a company that sells/sold seemingly magical money-saving space heaters nationally for around $435 -- nominally, anyway: Those Amish craftsmen are hard at work trying to keep up with the demand. My space heater is small and three-fingers-and-a-thumb light, and cost $15.97 from Wal-Mart. I love it!

You won't have to worry about the Third Law, or Nernst's Theorem, since neither you or nor your gear will be spending much time near absolute zero; unless the cable manufacturers come up with a new quantum effect that will, no doubt, unhinge your jaw.

So, unless you're worried about singed cats or blistered kiddie fingers, you can just figure it all pretty much ends up heating your immediate environs, regardless of classes, bias settings, or other such considerations. For a lot of electronic gear, I wouldn't want to believe the power consumption labels too religiously, unless the spec is backed up by real world certification. You can buy a gizmo to test your draw directly for pretty cheap these days, of course. BTW, that crummy corkscrew bulb in your reading lamp may not be saving you the big change this winter the manufacturers and hopeful magazine writers are suggesting. Consider the above... and think about it. We've mandated incandescents to a soon-to-be-upon-us abrupt oblivion anyway, even for central furnace weather. You'll enjoy the mercury residue and the optometrist's bills until decent LED options appear in abundance.

For more on Class A solid state and heat, take a look at a couple of the product manuals Nelson Pass has put up on his First Watt site -- they address heat sink temperatures explicitly.

One more BTW: Those conservation laws they talked about in school are intimately related to those abstract, mathematically esoteric "symmetries" theoretical physicists like to go on about, pretty much on a one-to-one basis. Interesting! Who'da thunk it?

I run an X-250 into totem forests. according to the meter I never get out of class A, and they wail, I mean loud (Real loud) in a 14x20 room. I can stick my fingers right into the fins after an hour no problem. Warm, yes, very hot, no. Does taht help? That's 40 w class A....

In general, I would say a SET will be hotter. I could put my hand on my Aleph 3, comfortably for 20 seconds. The hottest amp I have had was a Viva Solista, you could coook breakfast on that. It is'nt only dependent on the tubes with a SET, the Solista was very hot with 2, 211 and 2, 845 valves. I use an Ayon Spark too, the same 623C tubes as the Almarro and it is'nt that hot.
So it must come down to circuit design too, as well as the tube.
The clear winner as a radiator, was the Viva Solista

David12 makes a good point, tube type and overall design are factors to consider. My amplifier is 300b SET class A, 8 watts per channel. After being on all day(10-12 hours) the amp and transformers are only warm, never hot.I would think the 845 and 211 tubes as well as their respective power supplies will generate more heat.