I know that people talked of some form of suction or vacuum feeling upon first listening to the LCD-2 (version 1 or 2 at the time). I felt something similar - it was almost a physical discomfort of eardrum pressure (even at low volumes) and maybe that's also because I have tinnitus ? Regardless, I acclimatised to the feeling after a few days and have had no problems since.
Yeah I have that too, which to mee seems strange with open headphones. Still I'm not sure if that causes the ringing in the ears itself, but it indeed is a bit bothersome.