After receiving the brand new HD580 headphone, I began to compare it with the HD600 that I had on loan. The HD600 had a well-worn pads, and the drivers probably had more than several hundred hours on it. The HD580 was brand new out of the box with zero hour on its driver.
Out of the box, the sound of the HD580 was a quite dark, even for HD580/HD600 standards. And while the bass was not boomy, it lacked the clarity that the HD600 bass has. The midrange and the treble, though had very similar tone with the HD600’s, had noticeably less presence.
It didn’t take long, probably 30-40 minutes, before the HD580’s bass started to open up and show more texture like the HD600’s. I was quite surprised that the drivers changed that fast. Neverthless, the midrange and treble still didn’t have a presence like the one on the HD600. I began to wonder if the plastic grills that come with the HD580 was the cause of this, and so I swapped the grills on the HD580 with the metal grill on the HD600. There was barely any change in the sound.
Then I began to notice that the pads on the HD580 was still very stiff. The Sennheiser “death grips” was very strong with the new pads. On the HD600, this was not the case. The pads was quite well worn, and it was much softer than the brand new HD580 pads. The old pads were also much more comfortable to wear. So I tried changing the brand new pads with the old pads from the HD600. The sound is much more similar now. The treble presence and midrange has improved, almost like the HD600’s. Apparently the softer pads changes the distance between the ears and the drivers, and that changes the frequency response a little bit. There were still some small differences between the sound of the two headphones, probably due to the drivers in the HD580 only having a few hours of burn in time.
During the next 2 days I proceeded to burn in the brand new HD580 pads, by putting the headphones on a dummy head (like on the picture above). After the two days, I couldn’t differentiate between the two. The sound has become identical on the two headphones. I must say that in this case, the pads make more of a difference than the driver burn in did.