SSL Sigma summing amp from SSL allows you to work in the box but bring out your discrete tracks for final analogue world mix. People say it makes all the difference to the stereo image and dynamic range.
A new update makes it possible to control the Sigma via something like TouchOSC allowing you to control all aspects of the Sigma making it more akin to a full analogue mixer.
The update is available for free at the beginning of April.
Here's the original information about Sigma:
Sigma, the remote controlled analogue mix engine. Designed for the DAW user that seeks the legendary big sound of an SSL console while retaining the convenience of working in the box, Sigma is a unique analogue mix engine in a 2U rack unit, that is remote controlled using MIDI via Ethernet using a DAW or an iDevice compatible software interface. Using proprietary MDAC control technology first featured in the Duality and AWS studio consoles, Sigma's 100% analogue summing engine can be driven by automation data created within your DAW of choice. Sigma features 16 flexible input channels which can be individually switched between being mono or stereo for up to 32 channels at mixdown. There is accurate front panel LED metering for all channels. There are two stereo mix busses with dedicated outputs for convenient printing of stems back to the DAW and individual stereo insert points to facilitate implementation of parallel compression. Each input channel also features an individual direct output. Mix Bus B can also be injected into Mix Bus A for final mixdown.