Ok so I think I already know the answer but I gotta ask, sorry. We are in the home stretch of the basement build out and I was wondering do I build the riser then carpet or carpet then the riser on top of carpet?
Ever see carpet and pad that had a riser on top of it for a couple of years? It will never recover. If you build a quality theater in the basement it will only add to the resale value, Ripping out a good theater so that you have a blank windowless room makes little marketing sense. If you are converting a bedroom or dining room then there is some merit to that thought.
If you carpet first, you could always put your riser up on feet, that way you just have some small indentations in the carpet instead of the indentation of the full riser. But I agree with BIG, it's a waste of carpet for a basement build that will likely remain a theater.