HCR diary 20.6.1818 a musical party at Aders "Two Germans - Baur (brothers?) performed on the violin and violincello in so exquisite a style as to delight everyone -such sounds were bought from the violincello as I have never heard". The two musicians walked back with Robinson and complained that the French appreciate merit in music but the English not.
The only Baur alive then in music dictionaries was Charles-Alexis Baur who was a harpist, so these remain a mystery to me