Most subs are designed and designated for home theatre and are not recommended for audio systems. The exception are REL's, very "musical" subs. Another advantage of REL, you can use it in stereo system (high level connection) and at the same time integrate it into home theatre at the same time (low level connection). You can connect other subs one way only, either low level or high level but can't use both at the same time.
I use REL B2.
I use REL B2.