I hear and obey. But (and this is a confession) I hate organ music. Maybe it's because the parish I grew up in had arguably the world's worst organist with the most awful singing voice I have ever heard (I kid you not. When I was still a teenager, a friend attended Mass at my family's parish. The organist sang some solo part of the liturgy. My friend almost choked when she heard him. She turned to me and whispered, "Is that how he really sounds? I thought somebody was playing a prank!")
But back to the organ... Does this mean the great masses composed by Mozart, Beethoven, and Bach are off limits because they include other instruments?
No. Pius XII officially allowed orchestral instruments in his December, 1955 (?) encyclical on the topic.
Prior to his authorization, of course, the instruments were used, by Bishops who were frankly disobedient. (This goes to show that disobedience-by-Bishop is not exactly new.)
If you're close to LA, go hear Paul Salamunovich's church choir and organ. He's at North Hollywood...