@Xavier, yes, sorry! My current goal is to stay below 60C = 140F for surface temps. Power tubes will usually run 140C to 200C on the surface, FWIW.
@MP9, most components such as resistors and tubes will generate the same amount of heat independent of manufacturer or design, as long as they are working correctly in the circuit as designed.
The exception is transformers. A larger transformer will have more room for copper windings, which can then be lower resistance, wasting less energy as heat, and run cooler - they will also have a larger cooling surface, getting rid of their heat more efficiently and thus running cooler. But the cost of transformers is roughly proportional to their weight, and a larger transformer usually means a larger, thicker chassis to mount it on - so it drives up the cost pretty fast.
There is a more subtle design balance going on, with copper losses against magnetic headroom and core (magnetic) losses. But the net heat savings potential is fairly small, and the sonic penalties are (IMHO) not small.
