I agree with mgboy! I would recommend either LLT or IB. If you build an LLT it will respond "transient response" like a good sealed sub in the upper registers while still being able to go LOW. I have a my Magnepan MMG's playing with a SONO tube LLT "EBS" sub and it sounds GREAT. I was actually told by the Magnepan dealer that the LLT is the way to go with Magnepans. When I complete my home theater I am leaning towards either an LLT or IB. I don't have any experience with IB but I love my LLT.
GOOD choice on the speakers! Mine are really growing on me. I love the transparency, sound stage and detail for music while still sounding GREAT for HT.
Matt