[soundman98]

i really doubt it's going to be a defective component.

many of the factory radio's now come with preset eq settings to tune the radio to the vehicle it's installed in. if you're using just a flat eq with the new radio, there will be a noticeable difference.

with the pioneer's, very simply try toggling the 'loudness' on/off with the volume down--personally, i find the feature too much, but it might give you the extra oomph that you feel the system has lost. outside of that, you can also try using some of the preset eq curves in the radio to flavor the system to taste. just takes time.