Thanks again guys, finally i got the two units new the DP57 and DP67 run through my system plus my old DP 55.
At the end I kept the DP 67 because it was much more dynamic, i heared better resolution and more three dimensional sound. However I felt that the DP55 and DP57 are much smoother than the DP67. As i mentioned both units were new and i did not have enough time to play them more than 20 hours to reach this conclusion. So i really do not know if this will be the case after proper break in. Ill post my final opinion after spending more time with the DP67, and Ill definetly try to check the DP78 when i have a chance.
At the end I kept the DP 67 because it was much more dynamic, i heared better resolution and more three dimensional sound. However I felt that the DP55 and DP57 are much smoother than the DP67. As i mentioned both units were new and i did not have enough time to play them more than 20 hours to reach this conclusion. So i really do not know if this will be the case after proper break in. Ill post my final opinion after spending more time with the DP67, and Ill definetly try to check the DP78 when i have a chance.