Its hard to explain without the backup of pictures. I dont want to post any final results until i have the extra flats so i can experiment with them as-well.
The trick is distance. The flat is perfect distance for bass response, but for highs its too close. At the same time, the bowls are too far, and their cone shape adds the treble sibilance. I cut the "bowl off the bowl" so i was left with a 1-cm or-so dense flat foam ring (back of the bowl). I then placed this thin dense foam ring over the flat pad. This brought the HP enclosure 1-cm further away from my ear, yet with pressure of wearing the headphone, the pad formed a seal around my ear. The result is the sound of a flat, but with a more defined midrange and proper elevation to the high frequencies. Im also noticing more defined and solid bass, and it still dosent sound thin or stringy like the bowl. While it dosent have the imaging of a bowl, it provides a perfect middle-ground between the two. To me, i think its the most accurate sound, right at the best of both worlds. I want to try the same thing with my flat pads, cutting off the back of the flatpad and overlaying the top over the top of the flat attached to the HP-2, almost like a flat-pad extension.
Now, your probably asking my why i just didnt try reverse bowls... i did. These sound totally different. Much better in comparison. Reverse bowls just didnt do it for me sound wise, and there far to uncomfortable to wear long-term. These enhanced flat pads are perfect in the comfort department, and they sound just right.