I listen on the go. I commute an hour each morning and wait an hour and a half for a ride home. So carrying a couple of IEMs is impractical also changing to another on a crowded NYC subway could get you killed . So I chose the best all rounder which we both agree is clearly the M5. If I only listened to IEMs, I would have a few more. I am keeping the Solaris for the Treadmill.