This is Brian & John's forum. I'm to be forgiven this because I heap so much praise on Brian for every ribbon speaker he makes.
Would just one member with a VMPS ribbon at home (other than me) please try the $2200ea Sunfire True Sub Sig EQ? I wish I wasn't the only member to have heard it with a pair of RM30Cs, 626R or RM40s. I believe it best to use a high quality active high-pass xo on the VMPS ribbon. Distortion is lower, maximum output increased, dynamics even better, & greater ease throughout. In my case my pre-pro has a built in hp xo. If your active high-pass introduces a lot of distortion don't use it.
By my estimation this sub is the most affordable & easiest to use method to get the best currently offerred by digital EQ. Plus you get a state of the art 2700WRMS sub in a 13" rosewood cube. The sub sounds great x'd at 65 Hz internally with a second XO in series at about 80 Hz (the pre-pro). Beleive it or not, the RM30s were improved with a HP XO at 110 Hz! (Again, XO in pre-pro utilized. Improvement may be partially because of the huge 80 Hz room mode.)