fpomposo I have a hard time envisioning a competitive sub for say the budget to repair/retain the DD-15 ($800). I don't like the complexity (no adj crossover frequency aside from what receiver offers (often only 50Hz; I run B&W Nautilus 804 as 'small' front speakers, so 50Hz is ok but certainly not 80Hz that some receivers have as lowest) and inconvenience (no auto on/off) of running the DD-15 passive with standalone Class D (but have 2 on hand).
Unfortuantely, I have never had the chance to listen to the DD-15 in current large room setup or even compare to my 18" Dayton drive by LT1300 amp. I probably should close up the Velodyno and run/test with Class D connected to receiver sub out, see how it does. If that is already any good, then I assume together with repaired plate amp and Velonyne control would be even better, and certainly worth the $400 or so repair.