The DR-3 would definitely be a few sonic notches above your NAD amp. Succinctly put, the Classe is in a totally different league. They were considered one of the finest sounding transistor amps in their heyday. They were famous for being able to drive the toughest loads with ease despite of their low wattage. If you can find a used one in good condition, I say go for it! That's just my two cents...
Good Luck
Good Luck