N_Cook wrote:

An amp that works perfectly all right should not suddenly run noticeably
cooler doing exactly the same job in the same gig but just placing fag
packets, lighters etc , whatever was at hand, under each of the feet on the
base.

You don't understand equipment cooling adequately. It's PERFECTLY obvious to me.
It's all to do with the effect of back pressure on air flow.

Adding more space underneath the unit reduces the back pressure. It's a truly
cruddy design that they did it that way though.

Graham