Not necessarily it could be the AVC that is pooched on your radio the switch out will verify thisI thought the speakers on my '98 were blown, the audio was so bad while riding it.
Then after I got home, I started fooling with it in the garage and it sounds good. The CD is working good, and I have local stations that don't fade away while I am moving.
So, yesterday off I went for a road test... And yep, got up over about 50 mph and zonk! no more nice audio, it went all to pot. Turned up the volume and still a mess.
I don't know what kind of speakers I had in my '94 1500, but I listened to that radio at speeds up to 80 mph without any problems. Not so with this '98 1500.
So, something surely is different with the speakers, and just maybe with the wrong radio that is in it now.
I just received last evening the SE radio from you, and I need now to go about installing it and see if that fixes the problem.
If not, then a new speaker setup is in order.