2 to 3 rounds. Initial round would be a phone call when/if your resume is selected. At the end of the phone call you may be invited for an in person interview with a manager. If selected after the 1st in-person interview, a 2nd interview with a different manager (department and/or district manager) & supervisor with more technical questions is expected. References are expected from invited candidates for round 2

There are 2 in-person interviews. The questions they will ask you are very standard and easy to prepare for - pretty much any question you can find if you google "common job interview questions" will be asked. Of course they will ask about your musical background as well. I would strongly recommend spending time in the store and getting to know the employees before finishing your interview process if you haven't already. I would argue that the bigger part of the interview is to gage your personality to see if you're going to fit in and work well with your potential coworkers. You can be qualified as can be, but if the interviewers has any reasonable doubt that you may not mesh well with the group, nothing else really matters.