Hmmm... I think this could work. You'll have to excuse me, I get a bit dyslexic when there are so many cables types and connections going on.
So the stereo phono plugs from the TV/PS2/mp3 would plug into the switch box, and the RCA/DIN adaptor lead would go from the output of the switch box, into the Tape socket?
In which case, would I need the RCA/DIN lead to have four phono plugs (like the one you linked)? The switch box doesn't show how many phono ports there are for output you see...
The four phono plugs confuse me a bit, as I don't know which is for what... I've never been good with phono.
*edit* Another quick question... do you know where I could get some of the wood/laminate panelling from the Beo901? I wouldn't mind fixing up the switch box to match the amp... that dial + B&O styling would be too sexy!