Yep, the mains transformer still runs rather hot. It must reach over 40 degrees C. I've ordered an infrared thermometer so I can make some proper readings. I do however seem to have cured the mechanical buzzing the transformer made by mounting it on silicon bushes. I think I'll try attaching some heatsinks to it but it'll be a but tricky as the sides aren't flat.

Other than the hot transformer, the only negative thing I've been able to think of with the amp is that the power LED is too bright. I was just going to add an extra resistor but I think I might connect a pot in series instead and mount this where the volume pot went. I need to mount something there anyway to fill the hole so I may as well give it a purpose.