I have a wealth of music by Singenberger and others of his ilk. A few churches were throwing away....."that old crap"......and I "caught it" before it went to the dumpster!
I forgot "the rest of the story."
Singenberger taught the man who taught my uncle (who then taught me) about musica sacra...
And Singenberger was educated at Regensburg--remember? So was Cdl Ratzinger's brother, who last was Kappellmeister at the Domspatzen/Koln.
That's why Ratzinger has a good understanding of music--in fact, a VERY good understanding of music.