What role does software play in the final stage of putting polished sheen on the mix?  

Computer-based software environments are emerging as a very popular way of manipulating music and capturing the missing elements in your mix. The advantage with using software is it lets you micro-control the specimen music on your hands for sweetening the whole mix. If you have a good digital audio sequencer that is capable of automation, there are a number of do-it-yourself tricks in mastering that you can use to give a face lift to the final mix before planting it on your master.

Volume automation: You can use software to select the waveform and draw a volume envelope around it. With an analog mixer, the perfect fade may be elusive even after many attempts; the same can be achieved with a quick drag of the mouse along the software graphical user interface. Even at this stage you can pep up a sagging note and make your mix more intense.

Splicing and Crossfading: Another area where software is very helpful is if you have to redo a very specific area of the mix where your sequencer chokes. You can simply remix the problematic segment alone, remove the offending segment in the sequencer, and replace it with the new piece. Thanks to automatic crossfading, your choking bar will transform into stunning digitally-cured splice.

Unlike an analog device that embeds your compression layers, you can undo the compression added using software. Without the fear of ruining your mix, you can tweak the EQs and compression to your heart's content. You'll be surprised to know that your sequencer is loaded with the tools you can use to alter any or all of the attributes of your mix. Editing, pre-gapping, leveling, fading in and out, noise reduction and other signal restoration – you name it and the software lets you do it.