My experiences with the 150A Hot Rod are the exact opposite of Marakanetz's. I found the 150A HR to extremely warm and detailed without being colored. You are making an excellent choice for your husband.
I have spent the better part of 1.5 years looking for the "best" amp(as in all things, a personal opinion) within this price range and the Belles is at the top of MY list along with Monarchy SE-100 Delux monoblocks. If you look at the multitude of professional and owner reviews there is an overmwhelmingly opinion of true greatness and satisifaction. A fairly rare milestone in this highly opionated obsession called audio, especially within the "affordable" range.