It sounds to me, as you guys have said, that it's probably a gain issue somewhere, particularly somewhere not obvious, so... the software makes sense.
But before you get to that point you should have realized something seemed WAY wrong, then decided you'd take the signal path apart and inject a signal you know about. An iPod or iPad is most often that source these days: the headphone output is a bit lower than consumer line level, but it's in the ballpark. And volume level is likely to vary from song to song.
That's Dividing the Universe: if you pull apart the signal stream and plug a known line level into the power amp and it's totally quiet, the problem is downstream from there. If it plays like gangbusters, which it probably will, you know a)the amp and speakers can do it, and b)there IS a problem upstream. I've done this so often that when a problem crops up, I immediately envision the signal stream as left to right and I look for a place to verify performance. That's a strong tool that's very simple!
I'd leave the taps at 30W until I've seen proof that the amp is outputting anything near its max power level and the sound is not loud enough. You'll only get another 3 dB from switching to 60W, which itself says there's a problem somewhere else.
A good answer is easier with a clear question giving the make and model of everything. "The biggest problem in communication is the illusion that it has taken place." -- G. “Bernie” Shaw
