Hello,
The one thing that is bothering me is you said it is mostly happening when playing CDs. This leads me to believe it’s not the speakers. If you or a friend has another set of speakers I would try them out or even better put your speakers on another system. This way you can eliminate the variables. It sounds like a connection problem or maybe the input you use for your CD player is messed up. You can try another input and see if it still happens. Get the individual components tested on another system or systematically test each component separately. In the Chicagoland area I use this repair shop. https://www.deltronics.com/
Sometimes when I purchase used amps I have them check it out so I don’t damage my other components. I also had them install a better tweeter on my speakers. It made a big difference!
The one thing that is bothering me is you said it is mostly happening when playing CDs. This leads me to believe it’s not the speakers. If you or a friend has another set of speakers I would try them out or even better put your speakers on another system. This way you can eliminate the variables. It sounds like a connection problem or maybe the input you use for your CD player is messed up. You can try another input and see if it still happens. Get the individual components tested on another system or systematically test each component separately. In the Chicagoland area I use this repair shop. https://www.deltronics.com/
Sometimes when I purchase used amps I have them check it out so I don’t damage my other components. I also had them install a better tweeter on my speakers. It made a big difference!