Does anyone find any problems with this method of running speaker wire under the carpet?
Even with just 18awg speaker wire (no conduit) run underneath the thickest carpet, it will be noticeable when you step on almost right away, and within a few weeks you'll clearly see the outline of exactly where the cord runs. It's much better to run the wires through walls, ceiling, or under the floor, or an easy way, is behind the baseboard (you need to take the baseboard off anyways to put down carpet). 

Also I don't really get why you'd replace the wire once a year. Do it right the first time, and put wire in that will last for a few years. However, if it's due to some audiophile sound quality thing where you theorize that you can hear a 0.000000000000001% drop in quality because the wire is "old", I'm going to drive down there and smack you (see my recent response to a speaker wire question here).