Sunfire Receiver or Separates and Magneplanar Spea

I am not sure of the sunfire reciever that you are looking at, but as long as you have greater than 125 W into 4 ohms you are golden. The Maggies MMG-W and MMG-C system is fantastic, and if you read reviews, which can be believed by the way, one of the best values in all audio. Depending on budget and room I would suggest a small Sunfire sub (MK Jr?), a Velodyne DD-10, one of the Talon subs, or Rel. There are other good choices as well.

One thing that you will need, is the Outlaw Audio ICBM. It is a very simple analog bass management system. Your processor may do this for you, I am not sure, but if it does not, this is a great about $200 (used) solution.

This is a great choice, and you won't be sorry.

I'd be definitely doing separates with those powerhungry maggies, and cossing them up high! They don't handle dynamic power well, and are more "delicate speakers". I used to sell Maggies, and they don't handle the goods so well as it is. I'd cross em over at 100hz or so, and fiddle around, using maybe some fast 8" subs to mate up front with em.
While you can get a pretty, clear, and detailed sound from Maggies, getting em to handle dynamics is a challenge, to say the least. I'd go with maybe some Adcom or NAD separates for better power handling dubties, without breaking the bank.
good luck

From what I have been hearing, that set-up would not cut it for Home theater, what about looking at Eminent Technology Hybrid Planars? you need more low end for movies then the mags have to offer IMO