okay, I had been using pc38x for a year and selling it to upgrade for 6XX. I think I like the PC38x tuning more than hd6XX. The treble in 6XX sounded dull to me and the hump in the upper bass makes it sound a bit muddy compared to PC 38X. And for the resolution, I think 6XX has the edge a bit over PC38X. That’s all I think. I am wondering if my source is not enough to get the full potential of 6XX.