I have an old DT990pro 600ohm version (slightly moddified by me), as well as a DT770pro 250ohm version.
I thought my new DT770pro's would have the ear pads like my 990pro's, but to my surprise they were different. Bigger and harder, placing the driver farther away. I actually liked the old ear pads, but I can live with it.
Strange enough though, my DT990pro had a very very boomy bass, which turned out to be characteristic of the back of the driver enclosure. If you put your hands over the ear cups, the boomy bass would go away.
I actually Just recently moddified them and it fixed it! (I may post about my mod later). Basically though, if you take them apart, right behind the driver, there is a ring of some velvet cloth, and in the middle is a hole (which is right behind the driver's magnet). Well, If you can place something there to plug up the hole in the center, the problem goes away. I used a simple 3x5 index card, cut to a rough circle to fit in snugly. I also added something else around the edge of this, where the velvet cloth is.
Before this mod, I could tell my DT990pro from my DT770pro simply by listening for the boomyness. Now, after this mod, i actually have to think about it!
Still, I prefer the DT770pro that I have. It has better bass, and is more revealing. I got my DT990pro about a year back (although they are much older then a year old) for 130$us, and am very happy with them, especially after this ghetto mod.
~Towert7
