I was told by the people at AudioPrism, very nice and helpful folks, by the way, that it doesn't really matter which tap you use as long as all settings are consistent. It really is supposed to be a matter of whichever sounds better. Me, I can't really tell the difference, but I tried my 8 ohm speakers on all three taps and 8 ohm sounded somewhat better to me, so that's what I use. No help to you at all, yeah, I know, but that's what I was told.
