Soundstage is larger than HP200 in all directions. Bass quantity and quality is leagues better when you have a good seal. Imaging is about the same as HP200. HP200s are noticeably more forward due to how the driver is dampened (they could throw the same driver in a closed headphone, and it would sound 95% the same - they really dampened the driver well, almost too well for an open headphone). I don't compare sound signatures since I equalize all of my headphones. I can't compare to a stock AD2000 because I don't have a stock AD series headphone frame to throw AD2000 drivers in. I'd be too lazy to do the work for the sake of listening to something that I would never listen to anyway. Well, I guess I can say this. The GBH sounds like an AD2000 with a closed headphones' bass without the soundstage drawbacks of a closed headphone. People say that open headphones (that aren't planars) can't have bass? Think again.
Versus the K7XX, the GBH has much better bass performance, and due to how the driver is designed, it will never have the bass performance of the HP200 and GBH regardless of how I mod them. That's about it though. Everything else is basically the same, minus a wider stage on the GBH and better imaging due to the fact that the low frequencies are apart of the picture. Your typical open headphones are airy because bass is attenuated to the point that they barely influence imaging. Remember that I don't compare sound signatures. The use of equalizers make comparing sound signatures pretty irrelevant, imo. I have never heard a headphone that sounds good without equalizing them (or a headphone that doesn't sound better by equalizing), so I really don't care about out of the box sound. There's always some peak or dip in the FR that bugs me, so I gotta iron them out. Transparency-wise, they're all basically the same. Also, keep in mind that these impressions are with the HP200s having the beyer gel pads, so my impressions won't match that of a stock HP200.
For anyone wanting to attempt this, make sure you have a pair of earpads that are at least 1in thick and the bottom of the pads are perpendicular to the baffle. If not, you won't get good bass. I guess the Brainwavs HM-2 pads pleather could work, but you gotta stretch them a bit since they're oval.
Oh, and the AD2000 drivers are the easiest to drive, with the HP200s behind them, and K7XX behind those.
Edited by Trae - 1/24/15 at 6:45pm