The toroid and amps circuit fit perfectly.
30/12/07 - Managed to cram 4 channels of 3875 amps into this little box. It's a two-tier setup. The whole system now sounds really great but I'm having problems with hum on the second pair of amp (pulling hair...). Also I don't know why the new pair runs hotter even though they are exact same design.
7/1/08 - Upgraded the pots using two 100k ohms linear ALPS blue velvets. Result is not much difference.