Hi Mick, you can use most zorro 2 boards, and some zorro 3 boards (in zorro 2 mode).
There is also expansion for the powerflyer z4 and the mediator z4.
You could use the video slot, however you will need a video slot adapter if there is not one already attached. Amigakit had them in stock last time I visited the site.
Check out the BBoAH (Big book of amiga hardware) and the Amiga hardware database (amiga.resource.cx) for more info.
As far as the audio is concerned, you can either
1) attach the audio input leads to the audio out of your CD rom drive (assuming you have one)
or
2) solder the leads to the audio out connectors on your motherboard.
There is no audio header on the a1200 motherboard. Personally I never saw the point of having the phono out on the power tower (except to connect to the CD rom drive).
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