I have 2 M80 TIs in my living room with no sub and a pair of M3s in my office along with an ep175.
The living room is pretty big as the kitchen and dining room are connected to it with no walls in the way. I sit about 12' from the M80s and am currently running them off an Onkyo 5007 in a sterio config until I can aford the rest of the wish list for the HT.
The office is small at about 9'x12'. The M3s are close to my desk about 3' back 3' over and 3' up on the walls pointed down twards my desk. They are running off a HK 3490 along with the ep175.
How do they compare. Well thats not the easist thing to answer. I am really happy with both setups. Both have great tight deep bass for music and sound really good. At first I thought I liked the m3s more but the M80s have really grown on me. I think the biggest thing I like about the office setup is the slightly elevated position of them. Feels like im in the front row and they are right up on a stage on my wall
TBH I can't really pick the setup I like best and trust me I spend lots of time to trying to figure it out... I can tell you that before the Onkyo reciever came I tried the M80s on the HK and they did not sound very good. Once I hooked them up to something that could handle them properly they really came alive.
If you want to watch movies with it I think you might be better off getting the m22s and a ep350. For most music you dont need a sub with the m80s but if you want the rumble while watching a flic you need to go lower. Also keep in mind it is easer (cheaper) to get a reciever that can run m22s along with a powered sub then it is to get one that can drive m80s properly. If music is your primary concern and you dont mind them being more difficult to drive the m80s might be the better option and then later your all ready have the big boys to build a HT around.
