Hi Peter,
but why do you use two trafo's in the first place ?
Peter Daniel recommends 2 trafo's for bi amp operation. Each of my trafo's has 4 x secondary's by the way and had to be specially wound as 4 secondaries is not standard. One trafo would have needed 8 secondaries!!!!!
I forgot a bit, but looking at your picture again, did you put two (differential) channels in there ?
There are four "amplifiers" but each amplifier comprises 2 x amps bridged so in total eight amplifiers (hence 8 power supplies needed)! And oh boy they draw much more current than in non bridged operation. Heat dissipation is MUCH higher than before.
I did not have screens in my trafo's (again after discussion with PD) and based on the results I now get they probably would not make any difference (Nick has screens in his).
I don't think any torrodial transformer should acoustically hum in the first place
Right!! and mine don't NOW but they sure did before when they were located closer together in the box presumably because the EM fields of the trafos interacted. But just moving a couple of cm apart (in the right direction) and they are quiet now. Stacking them in the box probably would have been best but that would have needed a very tall box!!.
Paul