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.)