? for ya, Al

Hey, Al, I figured you would know the answer to a question that I have, so here goes. My system sounds best when I conect my sub to my rca pre outs for my left and right front channels, and then connect my amp to the xlr pre outs for my front right and left channels also. I'm wondering if this is bad in any way. When I shut my sub off, I can hear the amp in the sub doing that "fart" shut down noise through my front right and left speakers, so I'm wondering if the amp in my sub is cross talking with my power amp for my speakers in any way. I'm also wondering if havinv both rca's and xlr's connected for my front right and left channels at the same time is degrading the signal coming out of my pre amp in any way. If you are wondering why I don't just hook my sub to the sub pre out on my pre amp, the reason is because then I am forced to cross my speakers over at 80hz and this doesn't sound as good as running my speakers full range and using the crossover in my sub set at 40hz.

My pre amp is a classe ssp 25 and my amp is a classe ca-150, if this helps.

Also, anyone is free to answer this question but I'm sure Al would know, that's why I directed it towards him!