I've been messing around with WIN ISD and WIN ISD Pro, and have been throwing around the idea of making my own sub. I want a sub that can do both HT and music with music being the MOST important. I want the extension of a vented sub so I am probably going vented. I want the least amount of distortion possible so I was thinking multiple drivers... something simlar to the SVS PB2+ tuned a little lower. so I originally came up with two AV12's in a 250 liter box tuned to 18hz. Then I ran the same box and tune with a single AV15 and it appears to be very similar... My question is would I see any benefits from using two AV12 drivers instead of one AV15? My ultimate goal is low distortion, with great extension and "musical" bass... Also, would this design compete with the SVS PB2+? (which I got to hear over the weekend and was VERY impressed!) I'd probably get a Samson S1000 or S700 to power the sub. Any insight would be great! Thanks!