rdoc,
I'm hesitant to recommend much of anything anymore, but I agree with your statement about REL Carbon Limited subs. I sold a single JL Audio F112 v2 and replaced it with Dual REL Carbon Limited subs. My speakers are Monitor Audio PL500 ii, but the results are the same. They don't draw any attention to themselves, but they add to the overall sound like no other sub I've owned. I don't think they "hit" as hard as JL subs, but in my system they provide more shades of bass.
I'm hesitant to recommend much of anything anymore, but I agree with your statement about REL Carbon Limited subs. I sold a single JL Audio F112 v2 and replaced it with Dual REL Carbon Limited subs. My speakers are Monitor Audio PL500 ii, but the results are the same. They don't draw any attention to themselves, but they add to the overall sound like no other sub I've owned. I don't think they "hit" as hard as JL subs, but in my system they provide more shades of bass.