Turn it up! Turn it up!

http://www.youtube.com/watch?v=K3_HHZFi0As

On a more serious note, I'm really a fan of SuperCollider (especially for it's smalltalk-like dynamic language). It's incredibly good for sound design and real-time experimentation.

But for the best quality output, Csound (http://www.csounds.com/) is hard to beat. Here are some people who tried to recreate the same effect in Csound:

http://csound.wordpress.com/2008/08/08/the-thx™-sound-from-c...

http://joesprojectblog.blogspot.com/2008/03/thx-deep-note-ch...