A touch of brightness

[Womaz]

I would agree its probably your hearing as you are getting the same results with various sources.
I feel i may have a similar effect from my hearing, tho maybe to a lesser extent

It would also make sense that the PMC 23 would be the worse offender as they appeared quite forward in the highs, at least when i auditioned them. In fact when i auditioned them with a Naim system (which i feel is also quite forward and excitable) i was getting a continuous ringing where the high frequencies seemed to merge together. The only time i managed to tame this is to switch the music down to something like Bob Marley.

Out of curiosity what was your experience with the Sennheiser HD800? they are known for edging on the bright side

I loved the look and fit of the HD800, but the brightness was exactly the reason I went for the HE1000 in the end. The HD800s are awesome too, but I felt the HE1000 were as good in every department but lacked the brightness.
Trust me I wanted to like the HD800 more as half the price. I even used the equaliser in JRiver to tame the treble. This did help and at times I thought that I was going to plump for the 800, but as soon as I put the HE1000 back on there was no contest really.
I much prefer the look and fit of the 800, but its all about the SQ.