Most of the recommendations say double the lowest frequency of your speakers with subs I.E. 35hz set to 60 40hz set to 80, though with the H.P. version you could probably just leave it at the 40 crossover or full range no problem.
I have reg. M80s that I run full range with the help of my power Amp. Your MCA50 should have enough muscle to carry the low frequency power demands of the H.P.
Though beware the power of the M80 needs a powerful sub.
I have a PB1000 that couldn't keep up with my M80s. almost the same notes or range. So I added a EP500 though I'm a bass head and wanted to have more the dinosaurs in Jurassic park in my living room for my kids.
Cheers
So you're running Full range on the fronts and adding a sub to get more extra bass? I think my svs Pb-2000 has some powerful bass sonic I could feel in my chest.
