Got the DC filter (actually a PS Audio Humbuster) and hooked it up to the amp with nothing else on that circuit.

The 7700 still was making a hum audible from my listening position.

So after all that, I decided to just return the Outlaw and keep the B&K.

For those who can put the 7700 in a closed cabinet, the transformer noise isn't an issue, but I don't see myself ever doing that with my Salamander rack, particularly since I have my vertical center channel in the rack.

At this point I was just too sensitive to the hum of the amp (although my girlfriend also hears it, so it is there) whereas the B&K is dead quiet from the listening position.

Since there was very little difference in price (about $150 less for the Outlaw since it was B-Stock) as the B&K is a demo clearance model (with full 5 year warranty, same as the Outlaw) and otherwise no real difference in performance, I'm keeping the B&K.

Would I live with the hum of the Outlaw if I couldn't get a quieter amp for the same price? Not sure, but I don't think it's something that we should have to live with in a piece at this price point.

I grudgingly accept that the Xbox 360 is noisy at the $400 price point, however, I'd gladly pay another $400 for a quieter 360, but at $2000, mechanical noise is not something I was prepared to put up with.