Always mount output semiconductors on a heatsink, if a class Ab stage ensure the bias transistor/sensor thermally to them also.
You can't measure the DC offset of an active circuit without powering it up. And if the circuit requires a heat sink, you'll want to mount it to one before powering it up.
In this video I show how to measure the DC offset and gain of an amp with a multimeter and a smart phone:
Tom
In this video I show how to measure the DC offset and gain of an amp with a multimeter and a smart phone:
Tom