Thanks, Tony. Those were things that I thought of, forgot, and your reminded me again

You're absolutely right. Chances are the speakers aren't distorting, since that would be very difficult when their max wattage is 15 and the max for the receiver amp is 10. It's probably either the soundcard or the X10 system.

Is there such a device that can take an already-amplified signal from that 10W amp and boost it out on the other end, while possibly factoring in an EQ? I suppose I'll have to take a look, but if anyone knows of one off the top of their head, it would be useful

I'll still probably have to send that other panel back. I'm not sure what they were doing with it. You can see someone's fingerprints all over the back in some kind of dry residue that was left on there, and is all around the resonator (I guess that's what it is). Oh well.