These Free VST’s are a nice compliment to the standard  EQ’s  in your choice of DAW.  Baxter EQ in M/S mode is definitely worth having a look at for your Master bus. 

BootEQ mkII – ‘Musical’ EQ & preamp 



Nasty VCS – channel strip wit Saturation, EQ, Phase & compression

Nasty VCS


Baxter EQ – Mix Bus & Mastering EQ with L/R or M/S option

Baxter EQ