Started my own thread, felt bad hijacking kurts. Any other avalanche/atlas owners feel free to post your pics here. If you don't have the means, I can host them for you. Each avalanche 15" sub is approx 150L tuned to 19hz. One has 2 18" PR's. The other has 3 15" pr's. I will probably fill them with polyfill when I get the chance. My initial impressions are... Point of reference being the tcsounds TC2+'s (identical to av15mk1's), overall, the avalanches seem to sound less boxy, hollow, boomy sounding than the TC2+'s so in terms of SQ, it's a winner. In terms of pure spl, they both shook the house, but the avalanches do not bottom out like the tc2+ and seem to have much more headroom. Prior to these subs, I was using an SVS 20-39 CS+ and obviously it's not a fair comparison.. so I'll leave it at that Chad provided me with a general model of the avalanche 15" in this particular alignment. I don't have the means to take in room measurements. Sorry.