This may have been covered but w-to-wall carpeting requires, at the very least, what I'll call tie-down bars around the perimeter. Think - thin wood strips small nails pointing out of the top. Of course they also have to be nailed down. Without those, the carpet and padding just become a crumpled mess in short order.
The problem is if you have nice finished wood floors, I do. The problem being the holes in your lovely wood floors.
I thought it was fascinating to watch the carpets being installed though. They also require what they call (or used to) in the trade, a "knee kicker." It has a carpet friendly claw on one end and a thick but firm cushion on the other end. Shove claw into carpet, kick the other end. This is also crucial for a well behaved carpet because it ensures that there is zero slack that might otherwise cause a problematic lump or wave.
As for audiophiles, assume that the vast majority are mostly clueless. If you're worried about sound being reflected, carpet the walls first.