Today a parade of vintage cars, tractors and fire trucks passed my house, and I took the opportunity to better adjust the microphone gain for louder content. Except for some horns and bassy music which simply exceded the microphones maximum sound level, I think I have successfully found an acceptable setting. If someone is curious about the music: The songs Rosamunde and Liechtensteiner Polka sung by an unknown artist, the 80s new german wave band "Geier Sturzflug" with their song "Brutto-Sozialprodukt", and finally some more polka music I don’t know.