ghulamr,
A Y adapter has a RCA male on one end and 2 RCA females on the other. You plug the RCA male into the Preamp out and then use one of the RCA females for the main amp and the other RCA for the sub. You would need 2 for both channels (R&L). Do a google search I'm sure you have seen them.
What you have inserted in your post would work but looks to be more for car stereo. You can buy high quality Y adapters that won't degrade the signal as much.
ozzy
A Y adapter has a RCA male on one end and 2 RCA females on the other. You plug the RCA male into the Preamp out and then use one of the RCA females for the main amp and the other RCA for the sub. You would need 2 for both channels (R&L). Do a google search I'm sure you have seen them.
What you have inserted in your post would work but looks to be more for car stereo. You can buy high quality Y adapters that won't degrade the signal as much.
ozzy