Solid state amps do not require a load. In fact if they are making DC you most definitely DO NOT want a load on there.
Channel hums? You SUSPECT DC? Don;t suspect, get out your meter and FIND OUT. DC on a speaker can only damage the speaker, plus it stressses the amp and can cause further damage.
DC on a speaker will move the cone one direction and it will stay there. It usually hums loud in the bargain. A loss of a filter cap also makes loud hum, but there will not be a large DC offset.
If your output traqnsistors are bad, and you have DC on the output, it is FAR more likeloy you will measure terminals shorted together rather than open.
ALmost all DMMs have a diode test function. We use that to check transistors for basic function. They all work about the same, so the owner manual for most meters will explain it.