Has anyone added a small subwoofer to 2 channel and been thrilled with the result?

Bought 2 used RELs for peanuts (Ebay), easily helps make a good system great.

To answer the question I seemed to have missed, after hearing a friend's system years ago utilizing one REL and liking it, I was looking around on Ebay for any reasonably priced REL and found a Q150e that was missing its grill for 200 bucks. Had the grill frame though, and otherwise was (and is ) perfect...stapled a new grill cloth on the thing and used it alone for a couple of years...great sub, 10" front firing, lots of adjustability. Next I found a mint Q108MKII (8" downfiring) also for 200 bucks, and its addition to the mix is great...note that a lot of the tedious yammering regarding proper setup or additional electronic crossovers, room treatment, etc., can be ignored by simply hooking the things up and moving 'em around some until they seem to work. I use mine in mono (hooked up together to the same amp binding posts) as they're simply not directional as bass position cues come from somewhat higher frequencies, and the subs in tandem work together to cure some room issues. Bottom line...use in a room with furniture, hook them up an enjoy them...I made my own cables with Canare Star Quad, but many used RELs come with a REL capable cable.