Buffer amps. Been playing these for years, and no they just aren't all equal. In fact, the one that I built that cost the most and was the highest quality parts going in was not as good a s a less expensive one that I am working on now. Believe me, when it comes to Chinese products, I would rather bail, but if I am experimenting, then that is one route to go. Let me try to post some photo's of my latest project, just to show how easy cigar boxes make the project look as good as it sounds.