I think the big thing is the use of a digital power amp, which lets the receiver be smaller, lighter, cooler. From what I remember most of a modern receiver is digital anyways... with the possible exception of the volume control

M60ti, VP180, QS8, M2ti, EP500, PC-Plus 20-39
M5HP, M40ti, Sierra-1
LFR1100 active, ADA1500-4 and -8