Effects of using y-cable from pre outs


I have built in single channel sub cable. Older receiver only had 1 single sub output. I'm not about to tear into walls or add more cables. If I upgrade to an integrated amp with stereo pre outs...what effect will using a y cable to connect stereo outs have? Phasing effects? High noise?
aberyclark
I am using a Pass Labs Preamp which has dual XLR and RCA's out that are active. The XLR output goes to my Pass Labs Amp.

The RCA's are connected to a JL Sub with stereo interconnects from the Pass Preamp into the JL Sub.

Based on some of the replies in this posting would'nt this be a problem ?
Ozzy -- I took a look at the manuals for your Pass Labs XP-10 and your JL Audio F113. As might be expected with equipment of this caliber, all four outputs of the XP-10 (left & right xlr & rca), and both of the rca inputs which you are using on the F113 (left & right), are individually buffered. So none of the concerns which have been discussed here are applicable to your system.

Regards,
-- Al