I'm thinking of getting a mac mini to replace my aging XBMC-only original XBOX but I'm tired of the ridiculously extreme volume disparities in modern movie audio masters. I'd like to be able to run a software compressor (or anything else for that matter) over the audio output.
I'm thinking something like JackRack but native.
Update: ischeriad's answer works brilliantly, except for the nasty fact that the volume buttons on the Mac stop working. Is it possible to do this without losing volume control from the Mac itself?