I've not had issues with my Pro's but I did have an issue with the Gen 2's which was a faint high frequency noise in the Left. Apple would not replace for me the first time I took it in but then I spoke to the manager the second time (who I am familiar with) and he replaced it. The reason was that ears hear different frequencies and I could hear it but no-one else could. If its a sound issue chances are they won't replace.