Music transitions between areas

Hey, I’m about to set up music changes similar to a game like Banjo-Kazooie or King’s Field, nothing fancy, just a straight crossfade. I was wondering if it’d be most efficient to do this with an invisible rectangle at the transition points checking for collisions, or if it’s the same resource drain as checking the character’s coordinates all the time. I don’t really know how Unity checks for collisions internally.

Unless I have a gross misunderstanding of how it operates, a trigger would activate upon the event of contact, whereas location checks would have to be tested every frame (not counting options like dividing the game environment into regions, but then those regions need a means of detecting changes in their contents, which really just means that the trigger region is likely one of your best choices)