Ah, the thread title is X-desk VS Nucleus.
As Louie has already mentioned - Nucleus is only a controller with a couple of pre's - it will impart no 'sound' of its own other than the pre's if you use them with the input of a signal - nothing when you are actually mixing as such.
X-desk is a mini analog console - minus the EQ which you would normally get in an analog console.
X-desk would be perfect for monitor control, talkback and most important part is that you would use the X-Desk for its summing features.
Think of it like this - when you record into your DAW and you have a mulitple of tracks going to the master stereo outs all of the summing is done digitally via the internal mix buss - so your DAW is for the lack of a better word 'digitally gathering' (summing) all of your tracks together to output it via stereo L and R in a very computer like mathematical sense - 0's and 1's.
The benefit of using an external summing device is that you are sending discrete tracks out of your DAW into separate inputs of the summing device - these are generally regarded as 'stems' of the multiple tracks in your DAW - for example you might buss your Kick out of output 1, your snare out of output 2 and the rest of the 'kit' (toms, overheads, room mics) out of outputs 3-4, your Bass DI and Mic tracks to output 5, Guitars to output 6 and vocals to outputs 7-8 - then you would mix these 'stems' on the physical faders of the X-desk for example to the LR mix buss of the X-Desk - the way that the X-desk sums these signals together is in the analog domain - summing in the analog domain is a tried and tested process and tends to add harmonic distortion and other artifacts that are actually pleasing to the human ear rather than leaving it up to a computer to 'crunch the numbers' and come up with a mathematical alternative to summing the tracks together.
The beauty of the X-desk is that you can actually use it to sum 16 channels of your DAW outputs (thus allowing you to expand on how you either directly send out signals or stems) by using the ALT inputs which reside on each of the 8 main channels and selecting them via the CUE knobs and then selecting 'CUE to Mix' switch - this then adds a further 8 channels which can all be summed to the stereo buss - 8 being controlled by the CUE knobs and 8 being controlled by the 8 faders.
Also I have read that you can assign the Master Buss insert returns to the main mix therefore increasing the summing capability to a total of 18 inputs (although the insert returns if summed to the mix buss would not be fader or knob controllable).
I know this sounds a bit confusing at the moment but the more you delve into all of this it'll make more sense to you.
Also, Louie obviously uses the X-desk in exactly the way that I described - although like he says, he has to write all of his settings down on paper - to enable him to recall the settings at a later date. This is one of the reasons that I am reluctant to go down the X-desk path - I wish they had included Total Recall like they have in the X-Rack - but I guess this would have added to the cost of the X-desk (although not by that much I dont reckon) even though it would have been an awesome feature - i would say that it has stopped alot of people from buying them.
Another way to eleviate this probelm would be to use your DAW faders to do all of the volume control and have the X-desk set up at unity gain throughout, therefore making recalls a hell of a lot easier - but really you would want to drive certain signals through the X-desk to impart more of that SSL goodness onto your stems etc.
saggsy