Switchable live...

[note small crossposting] Hopefully a quicky question.
'92 Audi 80 (B4 Chassis) trying to wire in the cars first radio, there is ISO plugs behind the blanking plate but no switchable live to them.
Dropped the dash cover, checked power at the ignition, you've got a switchable live on the ignition on the smallish red wire when you put the key in [1], is that going to be substantial enough to power a modern stereo or should I be taking a more substantial feed from somewhere else?
I'd really like it on the key in stage rather than full ignition for moments like today sat in traffic when you know you aren't going to move for 20mins, or just having to sit in car can still have the radio on without engine running, nor a perm live as I recall this radio used to stay warm with the faceplate off when on a permanent live [2].
Prompt reply would be bloody handy from anyone as the car is still in bits ;)
TIA
[1] I never could find this bugger in my mk2 Golf for some reason [2] Currently a Kenwood 6024 MP3 player, likely to get replaced shortly... (bloody cd drives packed up)
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Jon B
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Similar problem on MK2 Golfs which don't come with an ignition live feed. One bodge is to run it from the heater fan switch as that is on a switched live (if the stereo runs off the switched live, don't do shite wiring. OTOH if it's just used as a signal, you should survive). You'll be able to get an ignition live from the fusebox if you want to do it right, but I don't know Audi electrics so I can't tell you where. You may want to find a later type ignition switch from a post CE2 (ie, any post 90 VW with the hazard light switch on the column) which switches the live feed as soon as you put the key in. This saves you from feeding the coil electricity when you want the radio on and engine off.
OTOH, you could just wire switched live up to constant live.
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coming out of it for live with the key in. If it is just a signal feed I may feel confident taking a feed off the wire that goes live with the key in (couldn't find a fused feed at the fusebox for it though that I'd have preferred).
When we get a spell of nice weather I shall probably investigate further, I've got something temp I'm happy with, but I can soon pick up a spare ISO plug and put something beefier in along side the factory job, if that perm live is the main feed that it won't carry much power so I'll run something fatter back to the fuse box. Getting at the fuse box in the 80 is simple, top side is in the bonnet, bottom half of it exits under the dashboard. When I saw the rats nest underneath I thought oh god what goes off under here till I realised it was the fusebox when I looked from another angle. So I'll hook into that and do something that looks more factory, try and find a safe route back over the steering column too as its a Procon-Ten model.
<annoyed> had past two days off, yesterday car sitting on ramps ingarage having cambelt etc, can't get at it, glorious weather, today car sat outside door, rained all day grrr.
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