No, I have the Reference 203*2, 202c and 201*2.
Obviously KEF tweaked the sound with the very large xovers in place, so removing these was not a good idea, giving a very uneven sound.
Also what I wrote on the little pots for the 7700, if you use biamping it will be quite handy to even out the biamped channels for gain.
That said, if you do xlr it will be a bit more complicated wiring the pots (but have a look at Rod Elliot's site for some info
http://www.sound.westhost.com)
When I started passive biamping (speakers xovers in place) I was amazed at the sound improvement.
I even tried triamping but that sounded not right (fuzzy) dunno why, maybe phase problems?
Use balanced cable for the 990/1770 combination by all means, I had a pre > Rotel RMB1095 5*200W
and it sure had hum problems that never really went away...
One more o/t remark: I just ordered a very special sub from Germany, it emits very dry bass down to 20Hz in a bipolar fashion (the chassis are placed opposite to each other!).
According to the test reports this should cause less oppresive room modes.
Barend