Radio questions of a general nature...

I'm actually very happy with my Radio Delta and the Bose system, as far as the sound is concerned...there are only 2 points...first of all the display is slightly defective (not really important) and secondly it's a cassette radio....that's why I had asked if a Concert 2 would fit and now know that there is the CAN bus and my A8 unfortunately does not have one....sad, because the Concert 2 would have been optimal...... listen to the CD without digging in the trunk and an MP3 box to the changer control - that would be cool....and the Navi -small retrofit would probably be easier with CAN bu

==References== Ebay gives a lot of Audi radios, I would be interested in the following information....

1. Are there actually different versions of the respective radios with / without Boseanlagen-Ability ?? Or can e.g. every concert 1 control the Boseanlage ?

2. I mean to have read here once, there would have been someone a concert 1 with CD slot......I haven't found one so far - is there the concert 1 possible from time to time with CD instead of the cassette drive?

3. Has anyone ever been able to compare the Delta with the concert in terms of sound quality - are there any differences or is it just a different design?

4. At the newer Concert 2 etc. Is there the possibility to control MP3 stories via the changer control - is there a way to do this with the older ones (Delta, Concert 1)?

5. Does anyone know which version of the nav computer for a small nav can I install maximum in an A8 without CAN bus? In case I see one on Ebay or so I mean....was version 3, or does version 4/4 DX still fit? On Ebay, versions 4 are offered more often, but there is no need for "....for CAN bus from 99..."

Thank you in advance for all the answers and greetings,
Alex