Thanks for posting in the community! Sorry to hear about the troubles, but would be glad to help!
Can you try and switch the RCA connections on the Acoustimass module? If the problem stays on the same side, this would indicate an issue with the speaker cable or speaker itself. If the problem switches to the other side, this would indicate something going on with the Acoustimass module or CD console.
Let us know how it goes so we can further assist!
Tony A - Community Support
Glad to hear it was just a cable issue! Regarding the second question, I wasn't able to find any information about the cable schematics. I would recommend contacting your local support center to see if they still carry the audio input cable for the system. Just click HERE and select your country and Contact Us at the bottom.