I sometimes use my sub with my small apogee ribbons and it does give them that full range sound and is very nice change of pace with them. As Thsalmon says,works best if sub is placed between the speakers. In my case,between,to the right and a little bit back of the mains. Hometheater placement does not seem to matter as much which is where my sub is used the most. The REL or M&K's might just do it for you,they are both very good and fast subs.
