OK I will try not to make this too long but I got an education yesterday
OK,
First to answer your question (thanks for the input by the way majorloser) The existing receiver does not have an lfe output for a sub just, a speaker wire connection for the sub which has always been hooked up to the passive Kenwood sub.
After researching the different ways to hook the system up I went out searching yesterday. I had kind of made up my mind on the Mirage S8 sub but wanted to still do a little checking anyway. Well I ended up at our local Sound Advise (Tweeter) store, walked around and looked at their clearance items, messed around a few more minuets and was leaving when a young guy stopped me and asked me if I needed any assistance. I told him not really that I did not think they had what I was looking for but he asked and I told him. To make a long story short I left with a Velodyne VX-10. Sounded great to me (keep in mind this is for a bedroom in a condo and the price was RIGHT) and it had two (R&L) speaker inputs and two outputs. SO I could hook them up with the right and left fronts set the crossover on the sub and then run my R&L fronts off the sub with it playing the down low stuff. This thing sits behind a large tall chest-of-drawers, and the Kenwood passive sub was much larger than I remembered so the VX-10 fit easily. Anyway ran new wires to the sub and then from the sub to the mains...... uh..... not real impressed. Then I thought oh wait you have your fronts set to small, so I went in and set them to large. It made a difference but I knew something was just not right. Playing the "Fellowship of The Ring" where Gandalf first comes face to face with the Balroc, when it roars at him you should know it. My main sub in my main system room (VelodyneDLS-R3750) will make it known when that beast roars. Now I know that the VX-10 is not the same but I knew I was missing something. So I hooked my R&L back up to the receiver in the normal fashion. I was thinking, just thinking, I know my receiver does not have an LFE sub output but it does have those speaker wire outputs for the sub, and I bet that that is where this receiver is trying to send all of the LFE. SO before I took it back I decided to try and just hook the sub-out speaker wires to the R side of the VX-10.
OH.......MY..... uh I hope the neighbor was not home, uh....... I think I just figured it out. And man I feel like I just stole a sub, for the price I paid. This thing would be just fine in my living room and then some. I know, I know only 100 watts rated 150 peak but WOW. Anyway this receiver just uses speaker wire to output to the sub, and it works just fine. Still going to get a Pioneer VSX-816 for the room soon, but wow what a difference. This will be my room sub from now on. There are better more powerful subs out there but I can't go much above 1/2 gain on this and it is more than enough. Sorry for the long post but now I know that there is really no difference between the sub cable and speaker wire for my system. The LFE can travel through a sub cable or speaker wire just fine.