There are a number of possibilities which come to mind. (1) In migrating from one platform to the other, you would have had to now use the OSX version of Lightroom (were you printing from LR3 before too?). Have you checked that all your program preferences and print settings have conveyed identically from the PC to the MAC version and that LR is indeed picking up the correct profile for printing? (2) If you are comparing the images on the new display with what is emerging from the printer, is it possible that the new display may be giving you a much brighter image than the old one was (recall there is no softproofing in LR so you are depending more on how closely the luminosity of the display mimics the reflected light and paper white of the print), indicating that the problem would be the possibly higher luminosity of the new display. (3) Or have you compared prints of the same image from both systems wihout any differentiating adjustments and the new print is darker than the same thing from the PC system? This would indicate the problem isn't perceptual viz a viz the display, but more likely a settings and/or profile issue. I believe the same image with the same adjustments and the same profile going to the same printer should deliver the same result whether it is Mac or PC.
Here are the answers:
1. I used the LR 2 CD, which is dual platform, to install LR on the Mac, and then upgraded to CS2.3 via the web.
2. Have not checked all the program and print settings to make sure they are identical, but will do that and make sure they are. LR is referencing the same profile for printing. The new monitor is definitely brighter than the old one. It was calibrated to 140. Should I bring this down? I guess I don't really understand how this affects the print. The old monitor could not adjust the luminosity calibration via software, so I have no idea what it was. But the new one is definitely brighter than the old.
3. Yes, I compared an image which was printed on the old system to one on the new (same image, paper, etc.) with no adjustments to image - it was just as copied from the old drive. Print was noticeably darker.
In addition to checking the settings, what else should I try?
Many thanks, Adele
PS Do you know the difference between the Epson profile SPR1800PtmLstrPhoto.icc and Epson profile SPR1800PrmLstrPhotoRPM.icc? ("RPM" added)