Hi Dana,
Here is another thought, and BTW, it's fun spending other peoples money. This suggestion probably won't be very popular on this forum, but it will save you a few bucks, and you might be surprised at good it is.
Go with an EP175. I had this sub before I had my EP500. It was recommended it to me by Alan Loft. I really loved the way it matched with my 80's, and gave lots of low end for music. I also believe that for music, sometimes a smaller driver is better. It can give a tighter sound, which is what you want when listening to music. It won't move as much air as a 350. But for music, that may not be as important. Your M80's are a full range speaker, and should play music quite nicely all on there own. I am guessing your not looking to shake the foundation here, just want to add a nice subtle bottom end when listing to your favorite CDs.
If I had a music only room with the M80's, my choice would be the EP175.
Food for thought.
paul
Paul,
Another fine option indeed(I could purchase a center with what I saved, close anyway), but...will the EP175 fill my 4200 cu.feet space??
Dana