Hi. You can hook that up, but you'll probably want to get a an RCA "Y" adapter (like
this, but they come in different forms) for the best results.
On some subs, you could simply connect to either the left or right input and it would act the same as plugging it into both. The
owner's manual for the SSW210 implies (to me, anyway) that's not the case with that sub. You can, of course, give that a try and see how well it works for you - just connect the subwoofer output on your Sony to either the left or right input on the subwoofer. I'd get the "Y" adapter myself, because they are really inexpensive and because it might make a difference, but I'd just plug it into one of the inputs until I got the adapter.