Don't start talking crap about made in asia stuff...
Most of the stuff you have in your house is probbly made in asia. Xcept you don't know about it. And besides, I don't think they keep making special, made-in-asia, crappy preamps just for you. I'm having no trouble at all with my speakers. Don't you see you're being illogical here? I mean, it's pretty obvious that if the speakers' design and construction were crap, everybody would have the same problem as yours. It is not the case.
I'm guessing the problem is with the speakers themselves, not the preamp. Probbly in the sub's enclosed amp. You should send back the whole speaker system and have them send you a new one.