Running th efinal at high power with 100ma bias means that at 12V your heating
them at 1.2W no signal. Bring that up to 24V and its 2.4W of heat.
To run at higher voltages you need to insure the heatsinks and air circulation
are adequate. Heat is a known killer.
However you will still be power limited as the drive level does not change with
increased voltage to the finals (separate power bus). So the increase is notable
but not hugely greater. HINT: if you don't increase the power by a factor
of 4 the other guy will not have a clue (he will not hear it).