Quick update.
I have decided to go with a separate PS for the LM4780 build (at least for now until I need my PS in a bigger badder amp). The PS is done!
PS specs:
*EMI filter on the mains input, IEC connection
*Safety fuses on the mains and on the secondaries.
*625KVA Toroid Transformer (Avel)
*Fast Switching Diodes (On-Semiconductor) that are heat-sinked and snubber cap'd (you don't often see proper snubbing in commercial designs)
*36,000 uF filter caps PER Rail for a total of 72,000uF! (Panasonic)
*Bypass caps on the output (Vishay)
*16AWG rail outputs
*Total cost was about $260, but I also had some stuff in stock already like the power switch and connectors. So, say total build in the neighborhood of $275 just for the PS. While that doesn't "seem cheap", this thing is a beast! It should be able to handle 400W continuous without a hiccup, and likely even more. I would put it up against most any PS and any consumer product. I should be set for robust and reliable power for decades now!
I have 1 channel of the LM4780 parallel amp completed and tested. I tested and measured it on my o-scope as 2 separate channels, then tied the outputs together in parallel config. After that, I tested it on my DT SM350, sounded great! The bass was amazing! I need to go back and scope it to be sure that nothing odd turned up when I did the parallel connection. It is installed in the chassis.
The 2nd channel is complete, but untested. My biggest hold-up right now--I ran out of thermal compound, D'oh. I should have a new 12g tube next week. I could possibly be done with this next weekend!