I spent time auditioning the Paradigm Servo 15 V2, Velodyne DD18 and ACI Maestro. All were very good performers with the Velo being the slight better of the three. Either sub would be good to own, all went low (25hz) with good performance and all sounded tight and had impact. Either of these units with proper EQ and bass traps works for HT and music depending on how extreme or refined your tastes and system are.
If I had to rank 'em
Velodyne DD18
ACI Maestro
Paradigm 15 V2
Good Luck
If I had to rank 'em
Velodyne DD18
ACI Maestro
Paradigm 15 V2
Good Luck