For multichannel audio, I prefer monopoles. The 370s would be an upgrade though, just as a pair of Minis would. If you do a LOT of multichannel hires music, I would say either minis or ADPs would be worth it. Surrounds are not quite as important, but it does make a difference (it did to me) to have speakers all the way around that match timbre well. I am using 5 identical speakers and I really noticed the improvement when I finally got the set of surrounds.
