From Uwe, thanks a lot!
This postcard is a part of a 'Greetings from...' series by Postallove. The series contains of 13 postcards giving the most important facts about a country they're from. The available countries are: Switzerland, Italy, United Kingdom, Estonia, Belgium, USA, Canada, Finland, France, Netherlands, Poland, Czech Republic and Germany. www.postallove.com.
The clarinet stamp is one of the Europa stamps, issued in 2014.