I have the SR-18EX and the complete code list for the SR-14EX (both higher models) and what you're looking for doesn't exist. I would have also liked direct speaker level adjustment codes, instead of the "Speaker" toggle button. Not there, alas. The only other initially interesting code I could find was "Volume Reset", which I thought might set the volume control down to nil -- which it does, along with every other customized level!