I had a chance to play with a DD15 for about a month awhile back. It's a very impressive sub, especially for music. I also had a 20-39+ in the house at the same time. The DD went back, though I could have kept it. The SVS outperformed it for HT and my system wasn't up to the caliber of the Velo for music. Well times have changed and my system now could handle the Velo, but I swapped out a pair of SVS Pluses for the PBU13. Subjectively, I appreciate the new Ultra even more than the DD for music and HT is awesome...textured bass, extremely tight, as well as, deep. The built in software and calibration tools on the DD are wonderful, though no bargain. The PEQ combined with room compensation on the U13 is pretty useful in getting relatively flat without treatments or EQ and is a bargain.
