I'm currently rendering a few AE comps from both a MAC and PC and have noticed a big differance in color and tone (the mac being more dark). I was wondering if there is an easy fix in the render settings to get them to match up (no CC as I want to avoid degredation from a secondary rendering.)Does it have to do with being premultiplied or matted?

I think it's probably due to one of two things:

1) The monitor and gamma settings on the individual computer (meaning, the file is the same, and it's being displayed differently)

2) The output format. Check all of your compression settings and codecs, and make sure everything is the same.

Yes the gamma of a monitor is different on a Mac vs a PC. Not sure why.

Right, but the situation I believe is in relation to how it's outputed from AE on a PC vs MAC. In other words if I take "comp A" and output from AE on a PC it looks one way on both PC and MAc. If I output it from AE on a MAC it looks darker on both PC and MAC. Wow if you can follow that your officially computer literate.

This stems from me completing my latest music video using trial versions of AE. When the 30 days ran out on the PC I downloaded the trial for my mac and continued to work. But the comps are rendered considerably darker on the MAC and don't quite cut. I'm hoping not to rerender the multiple comps!