Any good rooftops for a snack drink and some music in the evening.?
I am not so sure about the music bit and would recommend you double check any open-air bar for winter opening. Having said that, I really like the Vorhoelzer at the TU Building (Technische Universität München) for an early evening drink.
Hope this helps!
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The Grill - im Künstlerhaus is a beautiful setting with fantastic food and the prices are relatively reasonable. One of my favorite places in the city.