I use the Revel Sub 30 in my system but used to use two Revel B15 subs. The Sub 30 was quietly discontinued and I hear that there is a new "Ultima" level sub coming from Revel. I love the finish on my Sub30 in silver but the new Salons do not come in silver so I wonder of the new sub will.
Right now the Revel B15 is their only sub and I can tell you from personal experience that it is BAD ASS. Not the prettiest of subs but it sure sounds good. The setup software is very good too.
A review from AVRev.com that came up Number 1 on Google!!!!!