Perhaps a little update is in order.
I don't see too much comment on the SongSub, so I decided to write just a few comments.
When I received the SongSub, it took me a while to get it placed correctly and dialed in. It had more controls than I am used too, so it took a while to figure out how to use them. I still haven't attempted to use the PEQ and I believe I have it disabled.
For music, I am amazed at the speed and clarity of the SongSub. It blends together so well with the SongTower's that I often forget it's there. It really is a perfect match.
Since I don't crank my music as loud anymore, I never got a great sense for just how powerful the SongSub could be... until yesterday. My wife and I decided to rent Kung Fu Panda as I read it contained some good low material. Also, I enjoy animated movies (I suppose I'm still a kid at heart). During one scene towards the end of the movie, the SongSub rattled my house. So much so that my wife said, "Is that bad for the foundation?". I had to rewind it and watch it again. The impact was amazing.
I would highly recommend the SongSub for anyone who is looking for a new subwoofer. The price is hard to beat and the performance is top notch.