One thing that I have observed, in researching music supplements - Rice does not appear to have a music supplement option for non-music school applicants. To me, this says that (unlike other schools that don’t have a prestigious undergraduate music school), Rice is not looking to fill their bands and orchestras like some of their peer schools might be, since they have a music conservatory.
Although musical talent might might be appreciated on the application as an extracurricular achievement, for non-music major applicants it would not necessarily be a “hook” or an “institutional need” like it might be at other schools (not talking about applicants for the Shepherd School, who have their own audition process I assume).
However, it sounds like there are plenty of music opportunities for non-music majors. It is also nice to have access to the resources and facilities of the Shepherd School, for lessons and classes.