I have a 96 A6 with Bose sound system. The front right channel no longer works. All I get is a hum and sometimes a click. The speaker is OK since I swapped the left and right and the problem remained. Does anyone know how to fix this? Is the amp located in the trunk with the sub-woofer? Is this issue in the stereo head or the amp? Can the amp channel be repaired? Thanks to all.