CMSS3d is a god send when you have a 5.1 surround sound game a 7.1 surround sound system. Not only makes the extra speakers works, makes em not just clones of other ones.
For music, its pretty iffy. Matter of taste. Its not going to sound like intended at all, but it might sound better to you.
I really like the 24 bit crystalizer. Its great if you have low bitrate mp3's that have their range mangled. Its pretty good on cd's too but if you already have a good copy of a song its going to come out worse. Again a matter of taste, but i find it really helps with headphones.