I've been experimenting with Sonarworks and other similar plugins. I don't have monitors yet and most of my mixing is on my laptop in my office at work so headphones are a requirement.
Currently I use KRK KNS6400s but just ordered (MassDrop) Sennheiser HD650s which wont arrive until August 30 :(.
I found SW - headphone correction really helps my KRKs, but I still find I need to HEAVILY reference to know what they really sound like. Unfortunately, my evaluation ran out, so until I can afford to buy SW I just looked at the correction curve for the KRKs and HD650s and copied the Frequency and dB corrections into an EQ and saved that as a preset on my monitor bus (doesn't affect export there). As far as I can tell I get the same correction....and it's tweakable..so if i find I regularly have too much 450Hz in my mixes I can boost that in the correction eq so I am more inclined to mix that frequency differently.
Regarding amps. I contacted Sonarworks and Sennheiser and asked which ones they recommended...at least for the HD650 (which is a 300ohm speaker) and they both recommended http://www.schiit.com/products/magni-3 for $99.