The two (half) secondary winding voltages of 117.2 and 119.0V, being in antiphase will simply add to give you 238.2v

I assume you are worried about any common-mode noise only cancelling out to 1.5% (= (119 -117.2)/119). Is this the distortion to which you refer? Have to confess I don't understand the power supply arrangements for the two amps in your circuit

Apropos, your protection circuit operating within 1us. I do believe that such a circuit can be built, but feel that because it is so fast, it would be tripping all of the time. The RFI and noise will be of the order of 100kHz to 1MHz and I'm sure dropout and over-voltage spikes can be of this order.

Following this thread with interest.