XA7ES Variable out with JL sub?

I have been testing pre-amps and have again returned to using the XA7ES (variable RCA) output straight into my amp. How would I go about using the JL Sub in this configuration?
Use a Y adaptor from the variable out and go to the amp and the line level inputs of the sub. Radio shack has some decent gold plated Y adaptors

I have the XA7ES in my bedroom system, direct into a Parasound amp.
When I add a sub, I use a Monster Cable adapter.
I don't know the name of it, it has a standard RCA female termination going to a male, with a female RCA on the side.
You can put it on either RCA output of the Sony, and run the cable from your sub to it..
I don't really have anything more to add to what is said above but I wanted to say that it's cool to see that there are other XA7ES users out there. It's an oldie but goodie!
Yes it is! In my attempt to upgrade I found the best option was to leave it alone and look at other things. I had to go very high up the chain. I have gained some ground with the pc and room eq. However I still go back.
Thanks for the help. I will see how my Vandersteens do with full range and sub. I liked the sound crossed at 45 or 50 on my Aragon but missing some depth, separation and impact that XA7ES provides by going straight to the amp.