My AVR's and amp get pretty hot to the touch.
ie,
Denon AVR-4520ci, Denon AVR-3312ci, Yamaha RX-V2200
Outlaw Model 770
I have a old Carver M-1.0t that stays cool- SMPS.
The Denon AVR-4520 does not get very warm in pre-amp mode only.
Class AB amps run hot.
Class A amps run very hot.