There's not really so much of a DIY car scene due to strict regulations here.
I've seen a few non-chain shops.
I'm no in-car audio buff though. In fact I can't even remember seeing a radio in my current car. I'll look the next time I use it.
For other add-on parts, say roof racks, replacement batteries, windscreen washer fluid etc., the Migros and Coop DIY centers may have something.
https://www.microspot.ch/de/search?search=autoradio
Medimarkt also has a good selection on display.
By the way FM is going to be history soon. So shop for DAB!
Em? What regulations exactly?
I keep hearing those myths that nothing is allowed, best one was when someone on this forum wrote that it's illegal to get your car fixed outside of official dealership.
For example, if you want to fit larger tires than the manufacturer specification, raise the suspension, fit a sump guard, snorkel, off-road lights, winch, and roof rack... each one of those needs approval...
This is a good guide:
There's definitely less of a DIY scene here than in the U.K. or U.S.
Here are some of the reasons:
People live predominantly in multi-occupancy dwellings with shared car parks where regulations (there's that word I mentioned) state that people cannot work on their cars in the car park places.
In the U.K, you can even work on your car in the street. I believe I read that you cannot do that here.
As for the vehicles themselves, you cannot fit non-approved parts either - at least without quite a bit of hassle.
As for non-regulatory reasons - people just don't appear to do their own stuff here as much as in other countries - gardening is another example of where people get the 'experts' in.
But sure - if you've got the place, and the tools - you can do what you want.
I do! (I bought a house from a classic-car collector so I've got a fair bit of garage space!)