FOUND THE PROBLEM WITH MY PLAYBACK SYSTEM!!!!
First, I would like to thank all of you that helped me by provided food for thought as I worked through this problem.
I decided to first connect up my old single 18" bass horns in place of the LA128's leaving everything else alone. Sounded like crap with the same poor muddy bass response I was experiencing with the LA128's.
Next, I changed out the pre-amp modules, EQ's, Crossover, etc. and replaced with my old 1980's pre-amp modules 18 db/octive(Audioarts Engineering). Still sounded bad.
Next, I replaced the two QSC PLX-3402's with my old two QSC MX-1500A's and Presto, THE MAGIC WAS BACK! Clean sounding Bass response. Unbelievable sonic quality difference between the PLX and MX series of QSC. Now I did not have all the power that I want with the MX-1500A, but good quality bass was recognized. I purchased the PLX-3402's to get the additional power I would need for the LAS128's.
So, with that said, do my PLX-3402's need repair? Or is this the nature of the beast?
Thanks Much
Dennis