Originally Posted by Furious Knight
What kind of setup do you have? A .1 setup or .2?
As indicated, there is no such thing as a ".2" setup. Many people use 2 subwoofers, but it is not really ".2", it is simply ".1" with 2 subwoofers, in which case, as also indicated, a single RCA cable would be run to each subwoofer, anyway, and only one of the inputs, R or L, would need to be used at each subwoofer.
If their was a such thing as a ".2" system, with 2 independent and discrete subwoofer outputs, but you only had one sub, then, yes, you would use both inputs, one, R or L, for each of the separate subwoofer outputs.
Also as indicated, you can use a Y-adapter at the subwoofer in order to utilize both inputs, but this is not really necessary.