Originally Posted by SuperchargedMR2
If I had a non-JBL system I would just upgrade everything, HU & speakers & add an amp & sub.
I don't think there's any difference in the sound quality of the JBL system head-unit. You experience better sound because of the extra power from the external amplifier and slightly better speakers. I upgraded my base system with an external amp and speakers/subs. A great improvement from stock but the head-unit has a very high noise floor which is more evident once the signal is further amplified. I'm currently in the process of changing out the head-unit with a Pioneer AVH-P3100 (awaiting dash kit, steering wheel audio control interface, rear view camera, XM receiver and some warmer weather).