Subwoofer questions -- music only

I have a wonderful pair of Von Schweikert VR-1 standmount monitors that I currently augment with a single Martin Logan Abyss subwoofer. I'm curious about running a stereo sub configuration.

I'm not a bass freak, although I recognize the need for that octave below 60 Hz or so. I would like to hear what benefits stereo subwoofers might provide. I also don't have an unlimited budget. So . . . can anyone recommend a pair of subs at $1,000 or less that I might compare to my single Abyss? One choice would obviously be another Abyss. Is there something better at that price point? Again, I don't really care about pipe organ music, so a 10" sub would probably suffice, but I do need the ability to come off my amp OR my preamp. Thoughts? Thanks.