My two cents - One thing all responses have forgot is that you are using the McIntosh Pre/Pro. The C-39/MX-130 decodes prologic as well or better than most. Going to a lesser expensive DD preamp will NOT necessarily provide better quality decoding. One option, if you like McIntosh (as I do) would be to sell your C39 (about $1,200) and put those funds towards the McIntosh MAC-3 OR the MDS-4 and buy the MVS-3 for your switching.
Pro Logic vs. Dolby Digital, DTS etc
I would be interested in input about the relative merits of these formats. I now have a Mac C39 with ProLogic built in and as yet, have not actually used. Will now take a DVD (Elite DV 37) and wonder if i should spend thousands going to a new preamp-processor just to get DD or DTS.