I think we should clarify the regulator discussion a bit. The max input/output differential on the LM317 is 40V on the National spec. Since we are operating at 30V at the output there is plenty of room. But there is another reference point, the ADJ pin. The ADJ pin is sitting very close to 30V so that the voltage difference between any two pins on the device never exceeds 40V, in fact given the measurements made so far under load, doesn't ever exceed 10V. Only these relative voltages matter. There are no absolute voltages on these devices. However, these conditions only apply once the regulators are at the operating point. The real problem is on power up. If everything is discharged then the Out and Adj pins of the regs are at 0VDC. The IN swings up quickly possibly to over 40V because the loading takes some time to stabilize. The Out and Adj follow depending on how they are loaded. As long as the relative difference of 40V is not exceeded then the regulator survives. We should add this means 40V in the forward direction. The regs have diodes to protect against reverse biasing. It appears that with these transformers and amplifier start up the Out and Adj are following fast enough so that the max differential is not exceeded.. But, as noted, to be safer you can use the HV devices.