Do I need new tower speakers?
 

I swapped out the head unit. I believe I got all the wires hooked up right with exception of Sirius radio which I don't care since I stopped paying the service. Everything works from what I can tell except the tower speakers seem to crack/distort if I try bring up the sound for the tower speakers ( I have a separate sound control for the sub and the tower speakers that's mounted under the steering wheel). I have four separate tower speakers in cans mounted on the tower. They are Kicker K6-2 with a separate tweeter on each canister. I took the cover off one and the Kicker still appears in good shape. The rubber around the speaker is soft and not cracking. The boat does get stored outside and I assume the speakers are 4-8 years old ( I bought the boat 3 years ago and inside speakers had just been replaced with Focal's the year before). I use a Costco car cover to cover the tower and speakers. Any ideas? Could it just be the tweeter? Could it be wiring?