I currently have my rear speaker wires in my 2gs3 connected to a LLC, which is connected to my amp. What I would like to know is can i still conenct my stock speaker back to those speaker wires while still attached to the LLC, so i can still used the speaker and the subs?? Or will sound quaility be comepletly diminshed?

 

not a good idea. the addition of a speaker's varying impedance and resulting currents will cause some level of distortion, and will likely screw up the levels as well.

 

do you think theres any harm to testing it?

 

You wont hurt it. I have had my cousins mustang running both for a year now and it still sounds fine.