The original phone, QP400, made by MB Quart in the early 90s was some of the best headphone of its time. Later on German Maestro acquired MB Quart's headphone business and started making these under the name GMP400, which is the one you're seeing right now. These feel flimsy compared to the original, and you can tell they cheaped out on many areas. The cable is much thinner, the pads are not as plush and the plastics don't feel as high quality as the original model. Yes they're still made in Germany, but the quality as gone down to such a degree that you'll be better off buying hifiman.
A friend of mine bought these, said they sound too bright and brought them over to my house to compare with my QP400. Apart from the looks there is nothing similar, even the sound is different. Way different. Connected to the same amp, the GMP sounds much brighter than the QP. Whether or not due to insufficient burn-in is anyone's guess. But if there's one thing the two models share its the horrendous yokes. They don't extend far enough to cover my head, and the headphone, even fully extended, will feel small for many people. HD600/650, in comparison, is much more comfortable to wear. I don't think they can beat the QP400 sound quality wise, but in the comfort department they are the better one hands down.