but man it could heat a room The A21+ must be a who lot hotter.
This statement above is not correct naimfan, A21+ idle or at low level listening is drawing only 160w from the mains, as much as 2 x 75w light globes and with the size of those heatsinks they would be only warm to the touch. This amp would have around 8watts of Class-A on it. Sure if you want to pump it up to party levels, then yes it will get hotter.
Cheers George