The "x" means that the designator gets used more than once, "x" being the common variable used in algebra. It can be LR (left and right channels), or perhaps as in the case of R1, it is the choice of 6 resistor values for loading. It just made drawing the schematic easier. Or when anyone talks about loading they mean R1. So in the PICCOLO, there are 12 R1 locations. For gain you will see them labeled ABCDEF, corresponding to the values in the table of 47.5, 100, 221, 475, 1.00k, and 47.5k. Easiest to just follow the board stuffing guide provided.
jh
