I am running the Magnepan LRS with a Bryston 4BSST and it runs HOT with those speakers, I mean not that it can't take it, but still. Anyway I also have the 7BSST2 and would highly recommend those amps. If you have bigger $$ there are a pair of 1 year old 7B3 on here for mid 6k. Anyway as to which of those two sound better supposedly the cubed is a little warmer than the squared. As for monoblocks and subwoofers, I would say absolutely. I have REL T5s that have used with the LRS and they add a lot and the monoblock hookup with REL is a big plus. The mags were developed on monoblocks. Bryston recommends shorter speaker wires than interconnects which of course pretty much demands monoblocks. The 7BSST2 sounds better than the 4BSST as one would expect and they drive my Infinity Kappa 8s with ease. Haven't hooked them up to the LRS though. Sound good with the 4B the bass is actually pretty good on that amp but yeah get the 7B3 probably if you have the $$ and want that long warranty.