I used to listen to classic music all the time, but when one day a musician pastor answered to this question at christian youth conferance, i completely understood my fault. He told that there is no anything bad to listen to classic music but it doesn't give you heavenly Life, you don't glorify Him with listening to classic music. Instead of that you can listen and sing christian songs to glorify Him as much as you can and not waste your time, because He is coming soon.Amen