Please keep in mind that you can also use the CC-590 just as well... It really depends on the size of your room... small room, the 590 will be more then adequate, even is a medium size room. Large room, best to go with the 690.
The only difference with it will be how low it can reach, and how much more power it can handle giving you a bit more SPL with the 690 - but if you are crossing over to a sub, chances are - you are and don't necessary need the extra couple of deeper hz the 690 provides...
Good luck on your decision...