For a student that is better musically than academically…is it better to apply to a college through the music program or through their selected major? What gives them a better chance to get into college?
Given the limited details, I would suggest that you should put your best foot forward. There will be limitations of course (like the school you want to go to for English - an example of a selected major - doesn’t have a music program).
If a student has the ability to gain access to schools based on an ability (music, sports, etc.), leverage it for all it’s worth.
It depends on the program(s) that individual schools offer and what the student intends to study. Is there a conservatory program and, if so, it that something that the student intends to pursue? Does the school have a separate School of Music and how does that work with the university’s other schools and programs? Does the school require/offer an audition and does the student plan to do that as part of the application process? Will the student pursue music as a major? If so, how feasible will it be for him/her to double major should he/she want to do so?
Sending along a strong arts supplement certainly can’t hurt an application, but applying through a music program can be a whole other kettle of fish.