FWIW, I found the differences in toggle position to be negligible to nonexistent. Of course, that's in my system and may not be the case for everyone. IMO just having the iFi USB installed improved my system for the better...not night and day, but appreciably better. I'm waiting for my battery powered W20 server to arrive so we'll see if it still holds true when there is no ground and/or polluted current (in theory it should make no difference or with my new server).
Yesterday I received a couple of AMR's dual headed USB cables (Jeff W.) and I'm eager to play with them later this evening.
Just trust your ears Nick. There is a ton of banter re the iFi on computeraudiophile if you're interested.