Parallel Processing: EQ
Parallel processing a dry signal with a wet signal equipped with EQ boosts is generally how the Clariphonic from Kush Audio works. The result is a nice smooth boost with no phasing issues, something an EQ in series is sometimes at risk from. Some engineers have been heard to say parallel processing rather than in series is more of a fad and hence - they are some of the best mixing engineers in the world - they never use it. Why use it? When mixing in parallel the engineer is never fully committed to a sound, and is encouraged to find the sweet spot between the dry and the wet signals. The added dimension also promotes experimentation with the knowledge that the processed signal can be tamed by splicing it with the dry signal. The VBC from Slate Digital lends itself to parallel processing through the rack version of the plugin. Each compressor has a mix knob, and when each compressor processes the signal quite strongly the mix knob comes in very handy to tame the signal back. With the three different flavours of each compressor it becomes quite pleasant finding the sweet spot by pulling up the lower volumes without damaging the overall signal.
The other use is a homogenising effect, especially when used on busses and master buss. The game Limbo has a homogenising effect applied to the visuals of the game with a grain layer on all aspects of the image and a vignette. Parallel processing can be applied to the master buss to bring all sounds together. Another case in Limbo is the entire sound palette seemingly passes through a buss reverb, including the music. This is especially apparent when the tire-on-fire chases you back down the hill and plunges into the water. The rumbles and the swishing of a torch have the same reverb tail.
So does parallel processing instantly improve your audio production? Absolutely not. To get a really good effect you must always get every step of the production process to be as good as you can. It does however add another dimension to the arsenal of techniques and equipment audio engineers possess, so use it wisely.