The manual states the heatsinks can get VERY warm under normal listening and this has been consistent in prior reviews. I just purchased this unit and so far it is only minmally warm.It stays on 24/7 since there is no standby switch. It operates in Class A at lower volumes then switches to A/B according to the manual. This unit pumps out 450 watts to a 4 ohm impedance. Anyone out there familiar with this amp?