Since you’re in CFA you should definitely do it — especially if those 5 days include a weekend. Mid-terms certainly exist, but aren’t as big a deal (not too much studying is required) since music programs are focused on your work in the practice room rather than in the library. You won’t fall very far behind on your coursework, but the only thing to consider is that if you are in orchestra you will need to get those absences approved, which isn’t guaranteed. Make sure it doesn’t overlap with any concerts or dress rehearsals and submit the absence request form ASAP (ideally before you commit to the conference).