I've found the standard system OK as well. Not great, but OK. It struggles with deeper bass levels (i.e. rumbling bass) and will probably distort if you turn it up too loud. But apart from that it does the job. I ALWAYS listen to music when I drive and the standard system is one of the better standard car audio systems out there...especially in the A3 class range.
In hindsight I would've gone for at least ***.
Yeah i completely agree. For the average user listening to generic music and normal levels the standard system is perfectly adequate.
If your into more bass heavy music or like it very loud, the upgrades may be the better choice.
I would have gone b&o but I knew I'd be going custom at some point so didn't see the point