just my 2 cents
i would say, qualitatively, that if comparing to running my audio research ref 110 tube amp (8x kt120), if we call the heat output from that amp a '10'
a decent powered solid state class a amp - say pass xa25, first watt f5, belles sa30, pair of schiit aegirs would have heat output of say, a '6'
whereas a higher powered class a/b amp like hegel h20 would be a '3'
and then, the agd audion monos would be a '1'