I have tried many power amps between the $500 and $2000 range including Rotel, NAD, Outlaw, and some pro amps including Audio Trak and Inter-m. Some of these had standard transformers, some with upgraded toroidal transformers. To my ears they all sounded the same. The Rotel seemed to dissipate almost no heat, and the Audio Trak gets as hot as a George Forman Grill. But all sounded similar, if not identical, at least to my ears.
However, I have never listened to a class D amp before.