I have just ordered a GS-X Mk2 and Focal Utopia headphones. Auditioned the combination for over two hours with no fatigue or discomfort. Despite reports from some that the combination is bright I found it to be extremely transparent to both the source and the recording. I wouldn't have it any other way. Will post photos once it arrives and is set up.
I'm listening to this combination right now. Let's look at the FR responses for both shall we?
Utopia:
http://www.innerfidelity.com/images/FocalUtopia.pdf
Certainly not a bright headphone...have a look at how the treble is shifted / pushed back from 3kHz and higher...no 6kHz peak like the cough...cough...HD800.
Now the GS-X Mk2:
http://www.innerfidelity.com/images/HeadAmpGSXmk2.pdf
Absolutely dead flat FR response from 10Hz all the way up to an insane 100 000 (my hearing stops at about 18.5kHz...not bad for almost 45 years old). Distortion (%THD+N 1kHz) for headphones between 32 ohms - 150 ohms is between a low, low 0.0007 and 0.0008. So nothing "bright" there...just very low distortion an almost zero ohm output impedance for more than sufficient damping factor and gobs of power (almost 6W on hand) to drive almost anything you can throw at it and never have it break a sweat.
Now, both units are ruthlessly revealing of your upstream source (DAC, CD player, whatever you are feeding them) and your source music...so garbage in = garbage out in this case.
I'm using the very impressive Benchmark DAC3HGC to feed my GS-X Mk2 / Utopias right now and I am floored by the level of absolute clarity and transparency. Feed this setup properly and it will reward you for years to come! Congrats!