I am planning on a speaker upgrade in the near future. My setup is M60v2, VP-180, EP-500, and four QS8. I am moving my home theater to a largermroom in a new home and I'm ready for a higher end setup. My receiver is a Dennon 4311 and I currently do not have an external amp(s), but sending pre-amp to externals is something I may consider in the future.

I am considering buying the M100 pair and keeping my VP180. I have not auditioned the M100, but I have listened to other brand speaker that I am considering also. Speakers that I have listened to include Martin logan Theos and Ethos, B&W CM9, CM10, B&W 804 Diamond, Paradigm Studio 60 and Studio 100. I haven't auditioned yet, but would consider Paradigm 30th anniversary Tribute or Signature S8 if I was to get a great deal. I have decided that I do NOT like how the ML Electrostatis sound so I am not considering those any more. Of course all of these other brands are speakers are MUCH more expensive than the M100 by 2-4X, and I would need to buy their matching center to go with the pair of fronts. I probably will be staying with Axiom but I am looking for other opinions. What is the best way to describe the sound difference between M60 v2 and M100? I am 50-50 between movies and two channel music. My music tastes include classic with lots of dynamics such as Stravinsky, Jazz like Spyro Gyra, and also progressive metal including death metal like Dream Theater and BTBAM (between the buried and me). When I listen to metal, I want to hear and FEEL the same pressure levels and dynamics that I experience when I see their live shows. I don't know the exact room size because it's not built yet, but it will be a medium size HT room. Thanks guys.

For two channel music you will see a big difference, particularly on the bottom end. I noticed a big difference between the M60 and M80 in that region.

For HT, I'm not sure you would notice much difference.

If you want to upgrade the theater, I would go for more/bigger/better subs before changing the mains.

Dougie, the greatest difference would likely be in the lowest bass, where the M100s, if playing alone, would have the capability to play louder. Since you're using the EP500 to play these frequencies, however, there might be only a very subtle difference between the two(even on those Stravinsky items we discussed a couple years ago).

My thought would be that rather than new main speakers, a second sub, properly positioned to minimize the effect of room modes, would be a more significant addition.

I like the idea of two subs, and my Denon supports 7.2. In my current room I can detect areas were the bass is stronger or canceled out. Should both subs be thr same model and manufacturer? How well would a SVS ULTRA sub work paired with the EP500?

For the best results in partially canceling the effect of room modes, two subs, if not identical should at least be very similar in frequency response at the mode frequencies. The PB13-Ultra is certainly a fine, if somewhat pricey unit. I have no personal experience with it, but it seems that the response at most frequencies would be similar enough to be good in combination with the EP500.