In the Studio, on the main mixdown bus I use a Waves C4 Multiband Compressor, Waves CLA Mixbus ,  Waves Infected Mushroom Pusher and then a Waves L3 Multiband Limiter.

1)Waves C4 to glue the mix together.

2)CLA Mixbus plugin to glue(emulates the SSL bus compressor) the mix and Drive (warms) the mix.

3)Waves infected Mushroom Pusher. Add some MAGIC

4)L3 to get the level to -.2 peak.

FOH 

To glue the mix together you need as a minimum a compressor on the main bus. Put the ratio to 2:1 and not much more than 3 db reduction. (this emulates the SSL bus compressor). The problem with a regular compressor is if you have some peak in the mid range then it ducks the whole mix. A better solution is a Multiband compressor so if you get a peak of something (like a vocal). The multiband compressor will only compress (duck) only that band (Frequency band). A multiband compressor has a separate compressor for each of the bands. The Combinator below has 4 bands. A Waves C4 has 4 bands and a C6 has 4 bands and 2 custom bands.

If you have a Behringer X32 or Midas M32 you can use one of the first rack slots for the “Combinator” Multiband compressor.

You can buy a Waves.com C4 for $29 and use a Liveprofessor 2  using a USB Audio interface and insert using the AUX IN and AUX Out on your board. If you can get your mixing board to connect to a Waves Soundgrid server, that would be the best. Most big touring groups have this setup. Digico boards with a Waves Soundgrid card in the back of board. All the plugin run on a Soundgrid DSP server on the Soundgrid network. Waves has a free “Live Track” program that will let you multi track for your show.