I have a '93 Touring with the Bose system. Not too long ago the system started with a huge buzz/hum at any volume. Today I sort of tracked down the issue to the rear bose hose. After unplugging the hose the hum went away. I'm guessing a ground issue, but I'm not sure if it's with the hose unit or elsewhere. Can anyone give me some advice or steps to determine if the (now removed) bose hose is the issue or if there is an issue with the remaining system. I just don't know where to start. All the wires and connectors on the system look good so we can rule out mice etc

Thanks for any help. I'd like to keep the hose and get it working just to keep everything stock on the inside.