^^^
Agreed, the difference is very, very subtle to my hearing too (more of a tonal issue and not worth the hassle of putting th mics in my ears), but I have found the SP-TFB-2 plastic holders don't really get the mics very close to the opening of my ears. They position them closer to even with the outside edge of them. I and have wondered about trying the 4060's in my actual ear canal but haven't tried that. I suspect it may make a difference though and that suspicion was indirectly reinforced after an experience at the Head-Fi CanJam event last spring.
I had a binaural measurement done for the Smyth SVS visualizer that makes a binaural headphone adjustment based on tiny knowles acoustics omnis embedded in earplugs. They made a big deal about getting the mic capsules flush in the openings of my ears, much deeper than the SP-TFB-2 sit. They made measuremente of sound from 5 speakers set up in the room with me sitting in the center and with various head rotations to measure my HRTF including pina response, then another measurement with headphones on over the mics to adjust for the headphone response and their pina interaction. I asked about the mics and they said dpa 4060 S/N lead to a better response, but the knowels mic was smaller, less expensive and good enough for demo purposes, and that getting the mics flush in the ear canal was critical to a good measurement and result.
It was the most amazing headphone experience I have ever had, completely convincing that I was not listening to headphones but sound produced by external speakers in the room, despite taking the headphones off and putting them back on repeatedly.