9" is definitely enough, although since it is only 5' it probably is overkill. Like gonk suggested before, I would just get some cable ties or string and tie the two together outside the wall, plug them in and see what happens. It may save you a bit of work and trauma.

The problem with analog noise on a digital cable is the possibility of the noise voltage to be high enough to swamp the "0" portion of the signal.
I just did a quick Google search and it seems most HDMI cables are shielded. This shielding is to counteract any noise generated from other sources. Coax is well shielded also. I think it would be fine to pull thiese all together. Jim

one last note, the way its working out i have no choice but to run all the wire through the same pipe. all wires being, the plasma power cord, hdmi cable, and my center channel speaker wire. do you think there will be a noticeable sound quality difference for my center channel? should i buy shieled speaker wire for this run? would that help? right now i'm using 12 gauge aperion speaker wire. what do you guys think? like always i appreciate your expertise.

I would use the shielded speaker wire. Make sure you only ground 1 end of the shield. Jim

who makes shielded speaker wire?