use a splitter. it will not be a problem, and it's easy, cheap.
5 responses Add your response
Many subwoofers (you didn't say what kind you have ;~) provide L and R line outs (and sometimes a LFE out) so you can daisy chain one or more additional sub(s) to the one being fed by your preamp.
If your subs don't have this feature, and you must use splitters, my preference would be to put the Y-connectors (splitter) on the sub closest to the preamp, and then run the second IC from there to the second sub. (Basically making your own daisy chain.)