Sorry this took so long, I came down with strep throat and have been pretty busy catching up with work.
So I got my e17 in and have been using it with my computer via optical at home (only for testing since I have an x-fi titanium) and usb at work (where I primarily listen to music for hours at a time.) All I can say is WOW, this thing has the same amount of power as the front-port amp that is on my x-fi and the quality is almost indiscernible between the two. As a DAC this thing is fantastic, compared to my work computer's headphone out it is not even on the same level. As an amp, I can only compare it to an e6, which seems like a simple toy now... The e17 has so much power, I could never imagine listening at the loudest levels, in fact I am scared to even turn it up all the way with them off my head. If you adjust the bass to +10 (~15dB boost) these cans will literally shake around on your skull. It seems like the gain levels affect the bass a little as well. The amp seems relatively neutral at 0 gain but as you set it to +6 or +12 it seems to get a little warmer. I do not have the required knowledge to do a full review of this amp so let me just tell you how I feel. The money I spend on the Pro700MK2's: well spent, feel great about the purchase, but still wonder if I might get something else after a year or so of having these. I am thinking about getting a new open set for movies/gaming/music combo. Possibly jumping into the $500+ range here, but overall I am VERY satisfied with the MK2's. Now on to the e17 dac/amp: I am 110% satisfied here, I see no reason to upgrade this anytime soon. I got everything I imagined that this would be when I set out to make my amp purchase.
If you have any doubts that the MK2/e17 combo will satisfy your basshead needs just stop. There is no doubts here, in fact I highly doubt that you will regularly end up leaving the bass all the way turned on on the e17, it's too much at times.
Feel free to reply or pm me if you have any questions here,
Chris