LFE settings?

[Tagman]

Can someone please in general terms explain to me if it makes sence to run a subwoofer cable from the reciever to a Y-splitter that will allow it to connect to both the (line in) and the (FE line) on the subwoofer. Right now I have one cable going from the Onkyo reciever to the (line in) on the subwoofer, and not utilizing the LFE plug. I purchased a 7.1 system of Klipsch speakers with a 10" Klipsch subwoofer. The overall performance is excellent but want to ensure that I`m using my subwoofer to its fullest potential. I still learning and researching all the various information and want to make sure I`m doing this correctly. For example: I purchased the new Rush concert on blu-ray (Snakes and Arrows) which was done in True Dolby HD 5.1 and it sounds incredible; but does lack slightly on the bass sections; where my Eagles concerts are impeccable on both areas. Would this be due to how the subwoofer is reading the frequencies?