Can I run electrical cable and sound cable in the same conduit?
You really want to keep these separate in a high quality audio setup, as you will get interference...especially through a sub.

I would even recommend routing the cables in entirely different directions if at all possible to minimise mains hum. Is there no other route for them? As an example, my mains wiring is in the walls, so where possible I have my audio wiring in the floor or above the ceilings.

If you absolutely can't avoid running them together, get yourself a cable that has a decent screen and make sure it is earthed.