jbl 1200.1

I have owned two of these amps, in two different setups.  (The first one got stolen)  In case you do not own or are familiar with one (and in that case you may not be of much help anyways) they have a front and rear inputs which strikes me as odd for a mono sub amp. I understand they can balance out the fading, but I can't understand why you'd be running that much power without a front and rear amp as well.  I'll stop blabbering now...

I once heard from a buddy of mine that getting 2F-4M to use all the inputs would help the sound.  I went out and tried it, thinking if it did not I'd return the cables.  To my disbelief, it did work.  The bass woudl considerably louder than it was before at teh same volumes.  However, I was unable to tell if the sound quality got better or worse for I didn't have it for too much longer before it got stolen. 

Has anyone else heard of doing this, and if so, are there any disadvantages to doing this (degredation of sound quality) or should this have been something I should have done from the get-go on my second chance with this amp?

Thanks guys..