Alpine in 1991 mark vii issues?

[5.0lincoln]

Hi all,
I have a 1991 mark vii with and alpine h/u and Rockford fosgate speakers all around. The issue is when I listen to radio I can only go to about 10 on the volume before the speakers are maxed and sound like crap. It's annoying and I'm afraid to blow the speakers. Not sure what issue could cause this. Any help would be great. Bought the car with the set-up.

[maylar]

Does the car have a factory amp?

[husker77]

Do you have "loudness" on, have you tried adjusting the bass, or other tuning? Are the speakers just powered by the head unit?