How to Separate and Insulate AC and IC cables

My set up forces me to run my interconnects and my power cords and my speaker cables through a 3" hole behind my amplifier. I know this is audio sin, but I need to keep my components where they are; it's a custom built maple and slate wall cabinet/shelving system. I've thought about drilling two other holes down through the shelf behind my amp, which would separate the cables at that point, but I'm shy about drilling into my new cabinetry.

Here's what I'm considering:

I want to insulate my cables and cords from each other using some sort flexible tubing. I've contemplated garden hose, clear plastic hose, pipe insulation. Is this adviseable? What are the drawbacks of doing this? Anyone know of a cost friendly product that would serve my purpose?
If your cables are properly shielded, I wouldn't worry about it. What I do know is, that if there is a problem, flexible tubing won't help.

A better bet would be some braided copper shield, like Belden:

If you want it to look nice, put the flexible tubing over that.
Of the above, pipe insulation is best.
Thanks Riffer and Unclejeff. I appreciate your feedback. Thanks especially for the link to takefiveaudio. Of the two suggestions, I'm leaning towards the braided copper shield. Since the cables are all hidden, it won't matter what it looks like.

Unclejeff, what kind of pipe insulation were you talking about? I was thinking of the black, foam stuff. Is that what you meant?
Are you having audible trouble with interference with your power cables and interconnects? Have you tried temporarily separating the power cables from the interconnects? I doubt you will hear a difference. Do you really want to go into all the trouble and possible wasting your time in making pipe insulation and than not hearing a difference? I once tried to separate power cables from interconnects and also use the right angle rule. I did not hear a difference and I have a highly resolving system that costs over 28K.
I would first suggest, as Joey implies, separating the cables any way you can before buying any insulation. It might not be cross-cable interference at all.

Yes, I was suggesting pipe insulation...the kind in the plumbing section.

I had not heard of the copper shield.
I'm glad I posted my question. I'm a relative newcomer to high end audio, and as I learn new things, I tend to get fixatd on them--cable cross interference, for example. But your responses helped me to get back to reality, which should be based on what I hear, not what I read in the media. No, I'm not hearing any audible cross interference. I'm going to go home tonight and listen worry-free. Sometimes I'm too easily lead astray from the reason I love hi-fi: the music.