It may just be doing it's job.
PA amps are designed to provide sound to speakrs designed to blanket an area with intelligible sound, not for used in home systems with fancy speakers.
It's also possible that those speakers have a high-end tilt which will accentuate the amps noise factor.
Slap on a couple of 70 volt transformers and PA speakers in a large area and I'll bet the problem goes away.
But, it could have a problem. Call your provider.