I'm in no way an expert or an authority on this but I think there might be SOME merit to the theory of dirt clogging the filters and altering the sound. A very similar discussion / argument was going on in the PFE232 thread on head-fi on this same topic with respect to the older Phonak filters sounding different from the new one despite supposedly doing the same thing. But in that case, there was also a consideration for the fact that the filters looked different in terms of the filtered area being different sizes.
I am a v1 owner and while I baby them a helluva lot, I can't say for sure that there is no dirt in the filters or that the sound hasn't changed a bit without me realizing it. I use them very often so the gradual change in sound may have just gone unnoticed. Then again, sonic memory is kinda hopeless and I can't depend on it to compare how it sounds now versus how it did when I first got it. I do, however, know from my side by side listening with the v1 and v2 that they sound identical maybe up to 95-98%. The slight difference there was VERY likely caused by fit as I simply could get as good and comfy a fit with the v2 as I did with the v1. Yes, I'm one of those weirdos who found the v1s comfy and smexy! So I'll attribute the 3-5% difference in sound to that. Still, it did not sound like the v2 was any less warm or more had more treble.
I'm thinking maybe you're getting a different kind of fit with this v2 which seems to emphasis the highs and by virtue of that emphasis, the bass and warmth doesnt seem as much as it used to be? I'm just spitballing here, but it makes sense to me. YMMV tho.
I'm happy to announce that 20 hours of pink noise solved all the problems: the harshness of the highs is gone totally and the sound is warm and nice like before. Unless the filters gathered so much dirt in two days, from now on I'm one of those believers of burn-in...
Edited by meurglys0 - 1/21/12 at 7:02pm