Dave Pensado recommends these free plugins:

source:

Apparently, ( and I didn't know this, or if I did, I'd forgotten) there are some versions of PT that don't have a
phase-checking feature.
Pensado ( being the Avid fan that he is) recommends inserting this into the Master Bus:

http://www.bozdigitallabs.com/product/panipulator/
( I suppose this would work with any popular DAW platform, although many DAW's already have
phase-checking included as stock processors... I know Samplitude does.)

He also suggests these from Tokyo Dawn Labs:

http://www.tokyodawn.net/tokyo-dawn-labs/

Slick EQ, ( which is an EQ, as its name implies)
TDR Kotelnikov, ( Stereo Bus Compression)
TDR Compression ( Feed-back design instead of Feed-Forward )
Proximity, ( a pan-distance processor based on several psycho-acoustic models/algorithms).

All are available as VST 64 ( and 32), AAX and AU formats. So, PC or Mac.

I haven't personally tried any of these yet, so I can't comment or review; I just thought I'd post the links for those who might be interested.

:)

d.