Writing you a reply email right now. Summary is, I've found best results using the 950's stereo bypass mode and using an ICBM for bass management. Allows me to cross the RM-40s at 40Hz w/ no double bass. RM-40s can certainly be run full range, but I like the flexibility of being able to position subs near room boundries and the RM-40s more out in the open.
I've never used the 770, but don't think you'll have a problem. I use a Earthquake Cinenova Grande (similar but more powerfull, 300w @ 8ohm, 600w @ 4ohm) but I really, really doubt you'll have a problem w/ 300w.
Ask your amp question over at the VMPS forum at audiocirlce.com:
http://www.audiocircle.com/circles/viewforum.php?f=39 I think there's a user or two over there that has experience w/ this amp.
Anyway, I think the 950 and VMPS make for a great combo. Certainly audiophile quality on an extreme budget. I'm very happy with my current set-up.