As I understand, they break the ground loop just like you described. I was told "they pull the AC out of the RCA's" (I think).

Sorry, I don't have the brand. I should have got it before they put the sled back in. Maybe I can call and ask.

As of yet, I haven't noticed any degraded sound. Well, that could also be because my EQ settings are still not right. Other than that, the whine is gone. I have some other whine thoughts which I may post in another thread if they haven't been said before.