Paul,

However, when I listen to my stereo mixes in Pro Logic

Dolby ProLogic is meant for playing encoded "stereo" tracks, not normal
stereo tracks. If you play normal stereo through a ProLogic decoder you get
all of the problems you mentioned - "an overall eq problem with my mixes,
that have too much mid-high end." And sometimes there's too little high end.

Here's how ProLogic works: Anything panned to the stereo center is routed to
the center speaker. Anything panned left or right comes out of the front
left and right speakers. Any content panned to the center but with the
polarity reversed between the left and right channels comes out the (mono)
rear speakers. All of this is separate from the "Hall" and other effects
settings built into your receiver, which just add extra echoes and ambience.

You could mix for surround using ProLogic if 1) you listen through the
decoder as you mix so you'll know what it will sound like, and 2) you have a
way to reverse polarity to force some sounds to the rear speakers. But then
the mix will sound screwy in normal stereo. I use the Ultrafunk plug-ins
set, and one of them is a surround panner meant for ProLogic. When you drag
a track toward the rear it sends equal amounts to the left and right
channels, but with the polarity reversed.

All in all, this is not a very good way to do surround mixing.

--Ethan