I have a 91 S5 N/A with no mods, pretty much stock. I never had any problems with the radio, but when I finally got around to replacing the crappy aftermarket stereo with a new one, it worked fine for a while then one day just shut off for no apparent reason. I finally figured out that the CIGAR fuse isn't making a very good connection, and if I push down on it (towards the floorboard) the radio will come on but as soon as I let go it shuts off again. It's definitely looser than all the other ones. I'm really hoping I don't need a new fuse block and there's maybe a way to wire in a new fuse holder. I'm also a little leery about wrapping the fuse with foil or something like that. Any help would be awesome, I'm so tired of listening to Pandora on my phone while I'm driving. I can barely hear it over the exhaust...

 

If you are sure its just the fuse connection, its easy to rewire a new fuse link. Just cut your wires and splice in external fuse connector found at any autoparts store. No need to replace fuse block...may be a little ghetto but its easy fix.