Hi Audiofire
I just had a look at your system...nice. My advice for you in your room would be to add some nice looking bass traps to your corners. This will add a nice increase in midrange quality as some of the bass gain (distortion) that is added to the sound will be lowered allowing you to hear more of the mid/hi freq's.
Sub cable: Turn off everything but the sub and have a listen...the answer to your question is there.
Are you having a sub problems?
Dave