Finally, dedicated a little time for posting some Frequency Response graphs. I was still working on the last mod after sending two sets for evaluation to Marv and Hans. This last mod dictated for me to perform extremely fine cutting in the back of the driver and I was almost sure that it won't find its way to production. Have to admit that not without critique from Hans I have decided to actually look real hard for its implementation. After thorough research I now am pretty much sure this can be done and will be in production.
  What you see on the graphs is my test results of the unit with mods similar to ones Marv and Hans have dated 12.8.14 and that same unit after the aforementioned last difficult mod was implemented dated 12.9.14. This mod addresses all the minor complaints regarding 2db boost in the low frequency department. It brings about 50% reduction of mid/low frequency bumps that were accountable for some distortion issues along with slight midrange emphasis as per Hans's comment (it's a quite pleasant emphasis if you were to ask me, but I see the point in making it as flat as possible so those who like/need such emphasis to be present can always get it with upstream gear. To my surprise with this last mod resolution increased quite dramatically, probably this has to do with lowered distortion and decay, which is now at least 30% better. Hope this will address all the last little issues and I could finally put something decent in your hands.
   I am also posting FR of one of my units in comparison with that same unit's original FR before any mods were made, with original pads on the same rig with all the same settings.
   Last you can find FR of some other headphones measured on my rig so everyone could see it's all legit. All my measurements are 0% smoothed, what you see is what you get except for one thing. There is generally approximately 5db tilt distributed smoothly and evenly throughout the entire frequency range. Basically that horizontal line you see in reality is tilted from +5db at 20Hz to 0db at 20Khz. 
   
   Unit with mods for Marv and Hans vs last one with difficult mod:


   
   Original vs modified frequency response:



   Some other headphones frequency response measured on the same rig:

For Zero:

pervenets -- for people like myself that already own the Oppo PM-1/PM-2, will you be offering to mod them for a fee or will you just be shipping finished products.

   Yes, owners of the original PM1/2s will be able to send their sets in for the mods. Expect the price to be $699.00 for the mod and $1398.00 for the brand new set directly from Audio Zenith. All my sets will come with a plot of unsmoothed original vs modified frequency response for that particular set.

   I have spent a ton of time and effort on making my measurements truly reflect how we perceive our headphones to sound while coupled to our own ears. This explains why you feel they mirror very closely with your perception of the ones you personally heard. I personally feel these aforementioned sets do sound precisely how they measure on my rig and hope most if not all audiophiles with properly trained ears should and essentially would feel exactly the same way.
   Disagree with your assessment of FR of my Audio Zenith PM-2 set. 

Alex, if you don't mind, I just wanted to clarify a little. (And correct me if I am wrong.)

Alex's measurement rig and his measurement techniques are proprietary. That is why he didn't answer you directly about his rig and technique. His mods are also proprietary, being a commercial product.

I believe Alex's measurement rig and techniques are a very big part of his "secret sauce" to getting the mods done as well as he has.

Didn't you get guidance from people on this board for help in setting up your measurement rig? When did it become proprietary? Or is your pet bear doing something special during the process?