Designer in wall wiring - worth it?

Yes - 10 gauge,; the run to my room was short.

I really don’t want to wade into the specialty power cable debate, and for the record, I didn’t say in wall cables had no sound, but that power conditioners were a better place to spend your funds.  If you think boutique in-wall NM cable (i.e. Romex style) will change the sound of your music I’d like to know which attribute you think it’s affecting, and doing better than a power conditioner.  Among them: 

• Reducing noise in the audible band
• Reducing noise above the audible band (EMI/RFI)
• Reducing emitted noise
• Controlling AC voltage so it’s constant, and less prone to voltage sag
• Power factor correction or some other resonant circuitry
• Power regeneration

Or did I miss some other attribute or power transmission that is important here?  In every single one of those cases above, except perhaps noise emission we can find some example of a power conditioner has measurable benefits.  Not every conditioner will do all, of course, but the scale of improvement is enormous compared to anything you are allowed to do in the wall of a building.

I would offer - if going to the trouble of upgrading the in-wall path to the audio room, why not cleanup/upgrade your electrical grid for the entire house. My panels were 20+ yrs old and the cheapest contractor grade material, the wall outlets the same. The grounding was a very poor short spike. Having two dedicated lines to the room put in was great - but cleaning up the entire path was money well spent. The last two pages of Vince's paper sums it up well; in the paper, he also covers the in-wall path well.  A worthy read.....

If you're already running 12AWG OFC, there is nothing on planet Earth you can replace it with that will sound better. Because science.