I'm no expert, but I checked out the M80's low end frequency response on this website. It appears that these mains will start to lose strength when they hit 34 Hz and below. In my mind, that kind of frequency response is more than adequate.
If you set your receiver speaker parameters to 'large' for the mains, the amplifier will direct the lowest frequencies to them. Considering the efficiency of the M80 is good, you should really hear that full bodied sound @ 110 watts. For HT, I think you will be impressed (perhaps astonished) at even modest volumes.
If you really need that ultra low 20-35hz response, there's plenty of subs that will fill that role, but with the M80s, I'd say that is overkill.
Really when it comes down to it, it all depends on you and your ears. Give the system a listen, but don't be swayed by your initial impressions. Give the speakers time to break in, then assess the subwoofer issue--- I honestly think you'll forget this whole thing after you do this
BTW, I just bought an ONKYO SR800---I don't have speakers nearly as good as yours, and I simply LOVE my new HT experience!!!
Hope this helps...
