Interesting post Chris. I have some experience with some of the above gear.

A couple of questions come to mind, what is the output power of your Musical Paradise class D? What are you thinking you need to drive the ESL63's?
They are rated at 100W and you have 35W on tap, that would only be a few dB louder at full volume. It is surprising how low the power level is at normal listening levels.

I have a 100W (8 ohm) class D that I sometimes use with the ESL57's, though I doubt it would give that output into the nominal 15 ohm impedance of the 57's. It is based on the B&O Icepower modules and surprisingly gave a less dry sound compared to NCore modules at NEBO10, though into conventional speakers.

The Ming Da SE is a match made in heaven with the 57's, it gives more 'body' than any other amp I have tried. The output into 15 ohms is only 10W but it doesn't lack dynamics.
I use a sub, a REL Stadium copy, but crossed over at a low 40Hz.