solid state stereo amp repair question

[9 volt]

Hello, I've got a problem with a solid state amp I'm trying to work out. I'm getting pops of dc on the speaker. Question is - How do I determine whether the output transistors are faulty or a capacitor before hand. The other channel is working fine so I've deducted that the power part of the amp is working fine. Pops occur when volume is down so it appears to be the output part of the amp. Thats where I'm at- sorry for the off topic question. Thanks