You have to help me; my eyes are crossing up looking at all the different options. To start with I have 2 AV15's and a BFD. Initially I only want to make one ported box for one of the drivers and power it with at least 500 watts of real power but would like to use the same amp to power an additional identical sub in the future. I also need to have a subsonic filter and a phase adjustment would be nice. For the subsonic filter, either like to buy constant variable or make a DIY low-cut filter so it can be made to match the enclosure. What do I need to do? I hate the idea of spending $400 on one component just to get the SS filter (rane pe15) use and another $140 for something to convert from a home audio AVR out to a pro amp in. Can anybody suggest something that might help with all this? Do DIY low-cut filters put in series with the sub amp work ok? The Mackie 1400i has the SS filter but is a little short on the watts. What else is out there? The SVS black box is great but what if I need more than at 15, 20, or 25 Hz filter. What can I do?