Your quandary of 7x2200 or a single 7700 is not uncommon. There have been several discussions of this. Obviously, there's no right answer (you can find folks running both arrangements very satisfactorily). A stack of monoblocks offers some redundancy and dedicated power supplies for each channel, while a multichannel amp takes less space and less power cables. At times when you are running just two channels (stereo music listening), the two monoblocks may be more energy efficient but the multichannel amp would offer a much larger power supply for the two lone channels to share than the pair of monoblocks would offer. Personally, I'd go with the 7700 - it's a traditional class AB all the way through it's operating range, it will take less rack space (although it still needs some good breathing room for proper ventilation), and it takes only a single power cord to deal with. Having said that, it's worth noting that I don't actually have a seven-channel amp - I have a five-channel amp (an Outlaw Model 750) and a pair of Model 200's driving my mains, and I don't plan to make any changes to my amplification.
There are a number of Outlaw owners running Def Tech speakers very successfully, with both multichannel amps like the 7700 and with Model 200's or 2200's. Some of those owners may drop into this thread, but you may also want to run a search or two through the forum.
Are you interested in LFM-1 experience in general, or specifically in conjunction with the Def Tech's? I can offer some general LFM-1 feedback
in my LFM-1 review and even indirectly in my
SMS-1 review .
The 990 does not transcode analog video to digital - the DVI output only sees the DVI inputs.