I've been looking at the NAD T773 as well. I would hope that the swapping of output sources or levels for load, power and heat sensitivity, would not be audible. I guess they must be balancing the workload, so the receiver contributes equally to either speaker type. Based on the heat output required and resistance it feels, it achieves similar balance.
I had the impression that you could always get a little more power into the 4 ohm speaker, from the same amplifier if the amp could handle it. I would hope this design doesn't limit the power into 4 ohm as much as it increases the power into 8 ohm.
From my research so far the Nad T773 is pretty much one of the best out there, without going to seperates. Simple to operate, with easy remote and programming functions, as compared to the Harman Kardon. The honest power ratings to all channels running, is only met by a couple of companies out there. Sure there is better out there, but you might have to spend a thousand or more to get it, as in the case of Rotel.
Good luck,
Troy
