The GSX is major improvement over the Hugo amp sonics. You can just feel the power (and the delicacy, detail, and finesse) of the sound at the same time.
The Hugo amp can play loud enough, but it does not have the spaciousness and image definition and bloom of the GSX/2.
I'm sort of retracting my comments earlier of the GSX and the HD800 now that I've done more listening with more material. For whatever reason, there is more silkiness in vocals,
not fully tube like, but still sweet and not raspy like I have heard with other amps driving the 800s. And I do find myself now all caught up in the GSX/HD800 combo's insight and openness. I do still prefer the Ether and Audeze, but the HD800 now has its own charms and validity with the GSX. The GSX seems to have no real coloration and highlights the differences between the phones. So I highly recommend the Hugo/GSX-2 combination's sonics.
How much better is the GSX-2 over the Taurus MK2?
If I may, I had the Taurus MK2, which is an excellent HP amp; the GS-X mk2 is just so much more balanced, clearer & as a fellow Head-fi member told me, "effortless" which I think is the perfect adjective to describe this amp. The Taurus' soundstage was deeper but the mids were somewhat, not lost but a bit blurred at times. Not so with the GS-X. Depending on the production of the albums I listen to I'll adjust the Gain (H or M) & Volume (DACT) accordingly. The three HPs I've used so far w/the GS-X are the HD800 & HD600/650 in balanced mode all with superb results. One thing I try to remember when I listen to this amp : because the amp is so clear and balanced if the song I'm listening to has many different instruments along with background vocals I have to really listen attentively because nothing is coloured so all of the sounds flow (effortless) through and I try not to focus on anything specific which, for me anyways, can be difficult at times. Nevertheless this amp is the best one I've heard/owned so far. I know I haven't elaborated that much on the Taurus MK2 or really compared both but it's not one of my strong points. I just hope I've helped somewhat.
***Edit*** BTW if you're thinking of getting the Taurus MKII by all means go ahead, some consider it to be an "end game" amp & I would agree with them. As a matter of fact I wouldn't be surprised that some may prefer the Taurus MKII over the GS-X MK2. There really isn't that much difference quality wise and then one has to take into account personal taste. The Taurus is an exceptional amp IMHO.