I have learned from Robert K. Massie's biography of Catherine the Great (a great book I have just started reading) that Catherine the Great was one of those people for whom music gives no pleasure (Nobokov was such a person). Her husband Peter was also (according to her account, which might not be that reliable) a lousy violinist. How unthankful it must have been for Anton Ferdinand Titz to work for an employer (appointed for life, probably) who hated music.
Here are some recordings of music by Titz, and a short talk in German about him that are on YouTube;
And there are even a a few sonatas for violin and harpsichord. I encourage anyone with manuscripts of this music to either scan them into the Petrucci Library or send copies to me, and I will make modern editions to upload.