Hi there, new to the forum here... great site, very informative. I've no previous experience with AUDI sound systems, but some with other cars, limited to upgrading to aftermarket HUs and amps though, nothing too technical. Just bought an A3 Quattro 3 door, year is 2000. When viewing the car before sale, it had an ipod HU with a screen, but the guy didn't want to include it. He said he would just put the Concert HU back in, which he did. It has a 6 CD changer in the boot, also a BOSE amp on other side of boot. The HU has a tape deck on it, and when powered up, it displays BOSE in the display. First thing I noticed was the eject button on the changer doesn't do anything, not even a sound inside. I assumed the guy hadn't connected it up to the HU. Wrong assumption? - I dont know. Then, regarding the sound from the radio (great reception but sounded odd), I noticed the front passenger side main (lower) speaker had no sound, but that the little one further up on the door with higher freq did. The opposite is true of the driver door, with the smaller speaker not producing sound, but the main speaker works. So, with the imbalance noted, I checked in the back, and you could say the main (lower) speakers have the same problem, only the other way round. In short, I can hear left and right, but left in the back, right in the front, and one small (mid-range?) speaker working front-left. I also notice there are tweeters front and rear-side of the door piller (at the top) and these don't produce any sound. The sub in the back is working. There are no parcel-shelf speakers. I count 10 speakers + sub, should they all be working? I only have 3 working, as described above. The following controls on the HU have no effect at all - balance, fader, bass and treble, is this due to the BOSE set-up, and in that case of no matter? I have just ordered HU removal tools off ebay, so I am awaiting those. I thought I would whip the HU out, and have a look at what's behind, and what HASN'T been connected properly.... although I've tried looking over this board and some other googled areas, I'm not sure what I' going to find. Does anyone here recognise these symptoms (obviously I want to get the changer working and have a balanced sound throughout) and could tell me, or hazard a guess at, what the previous owner has done here? I will get right onto it when the keys come, and hopefully have a clue how to root the problems out. Thanks in advance.