Hi, I use HD650s (with headphile black cables) for writing / rough mixing. I heard a friend's HD600s the other day and to me, they sounded a lot better, so much so that I thought maybe my HD650s are damaged or worn out. The HD600s had a lot more high detail, making it sound like frequencies were missing from my HD650s. They also sounded clearer than the HD650s, which in comparison sounded muddy/warm. It seemed that I could hear different parts more clearly and so more useful to me for writing/arranging... The HD650s had more bass.
I've used my 650s a lot over a few years so is it possible they're worn out and need some technician love? Or are these differences I'm hearing just the differences between these 2 headphones?