Newbie on subs - need hook up advice

My Rogue 66 preamp has only one set of rca outputs. If I use "Y" connectors to create 2 outputs at each of the left & right channels (one set to go to the amp & the other to go to the sub) do I need to use an additional "Y" to bring the outputs(the ones going to the sub) back to one cable which would then go directly to the sub??? This is difficult to explain and hopefully someone gets the jist of what I am trying to accomplish.
Buy an electronic crossover. Connect the pre-amp to crossover and low out put to subwoofer(s) and high outputs to speaker amps. If your sub has low level inputs (ie from pre-amp) it should alo have low level outputs that go speaker amps. I suggest strongly that you do not bi-amp by connecting pre-amp to 2 sets amps w/o x-over. The sub -woofer will try to produce high frequecies which it can't except enough to muddy your sound by causing wave cancellation. The intro of a cross-over will be startling in terms of clarity. Cross-overs are hard to find. You can buy a kit from www.marchandelec.comm for $250. Pro-sound guys are big on cross-overs and DBX makes a good one.
Go visit ACI (audio concepts) web page there is a full article how to "hook-up" your "sub", be it reciever or monos or just one unit amp. Save yourself a headache!...luck
If you are using only one sub, and your sub only has one RCA input, then yes. If the sub has a left and right RCA input, then no.