Hello all, I'm new to the forum. I have an Audi A3 1.8T 2001 (5 door) with the Symphony HU and Bose upgrade. There is a problem with the sound and I hope someone help me understand what is happening. *** My problem is that bass frequencies disappear when I set the fader/balance fully to the Rear/Right. *** It looks like the BOSE sound system has a total of 8 speakers: 2 tweeters in the front doors 2 low-mid in the front doors 2 low-mid in the rear doors 1 bass enclosure in the boot with 2 built in bass drivers (subwoofer) I disconnected the in-boot sub woofer only and found that the: - the sound is perfectly balanced from the rear door low-mid speakers. - rear doors low-mid speakers have no bass whatsoever. - front doors low-mid speakers have some bass (obviously not as deep/loud as the subwoofer). - when reconnecting the subwoofer, the sound disbalance reappears. It sounds like the boot subwoofer is connected to the left channel only. This is obviously not normal, can someone help me understand it? Many thanks for any advice.