With proper grounding you could run them within a few inches of each other.
Do your "quality special shielded audio cables" have a drain wire (a wire attached to the shield on the cable) on either end? If they have a drain wire you can attach that (via a ring terminal) to a good ground, make sure it's only on one end of the cable or you'll create a ground loop (an antenna that picks up extra noise).
If not just make sure the power and audio cables don't run next to & parallel with each other and keep at least a few inches separation (like 5"-7").
Power cables will couple with data cables and introduce noise into the data cable when their EMI fields interlace, usually when the two are run parallel with each other.
There are some formulas and factors based on the power & awg that may be found on Google if you want to get extreme...