thegm,
I'm going back your idea because I built a GR Research sub about a year ago. I just happened to have had a cabinet that I made for passive sub many years ago and used it. My compliment to GR Research was about the quality of the driver and the amp. Plus, it came with many ways to 'tune' the sub to my system. If they build products for active subs this well, then it carries into their speaker line as well.