Velodyne SPL 800 II vs. REL quake/Q108E

I am interested in purchasing a small sub for 2 channel music use only, to suplement my Tyler Acoustics Ref monitors. I am looking for a small sub that is visually unobtrusive, fast, and won't overwhelm my 10ftx 10ft room with bass. I am leaning towards either a velo spl800II or REL quake/Q108E(i have some confusion about if the quake and Q108E are the same speaker, if someone could clarify that for me). Which would you chose, or would you select another speaker. I was also considering the ACI force, but it seems to produce a little too much bass for my small room. Also slightly interested in the Rocket AV123 subs. I want to keep it under $800 new.
I have the REL Q 108 E matched with Von SChweikert VR-1s in a room that is 10' x 13' with a vaulted ceiling. I have been happy with the REL playing below 40 Hz to augment the bookshelf speakers. I haven't heard the Velodyne. Good luck!