[morzh]

Or another way, I simply would connect a scope and, while feeding the amp a sinewave, bring the idle while the crossover "step" disappeared.
If you feel the idle is too much, then bring it down a notch, as long as you cannot hear the step or it is barely noticeable on the scope.

There is a nice arrangement on an amp I built long time ago for myself with self-limiting of idle using feedback, I could set it as large as 300mA and there would be no thermal runaway.
An old and less efficient way to control the runaway is a thermistor in parallel with the trimpot that is mounted on heatsinks.