The player piano we had at home was QRS.

I now vaguely remember a string of intermittent holes running along one margin of the piano rolls that may have had something to do with adjusting dynamics. Also, some of the note holes, instead of being continuous, were dotted. This may have had the effect of decreasing the air pressure and consequently lowering the dynamics, but I'm not sure. I certainly don't recall the sound volume on the player piano being affected by much other than the amount of pressure applied to the activation pedals.