Best Small Sub? Sunfire, Velodyne, Rel, Def Tech

I am looking for a small sealed sub for 100% music duties. I already have a SVS ultra for HT. I will be mating it with a pair of Sonus Faber Conertos. I am considering a Sunfire MKII or Junior, Velodyne SPL or HGS, Rel Q series or a Definitive Technology Super Cube. I am looking for models with a 10" or small driver. Anyone compare these subs? Any opinions will be greatly appreciated. Thanks.
Rel all the way... I had the Concertinos and found all but the Rel very difficult to integrate seemlessly. For my money the Rel subs are significantly better, much more musical, than all you mention (I have no experience with the Def Tech you mention).
The REL Q201E is a small sub that will perform like a big one.
i have owned the definitive pf15 sub before for home theater and it was a decent sub. I currently own 2 NHT sub two subs for my home theater and for ht use, they are very good. For audio, I use a REL Strata III with my totem model 1's. Excellent sub for audio. I agree with Peteinvicta1, REL all the way!