Like, Evshrug alluded to, it's a matter of priorities... What are you most concerned with: PC gaming, console gaming, or music? Snobbery aside, the E17 isn't any better of a DAC than a decent sound card, better amp possibly (better than most cards, not better than an STX's/Creative Zx's amp tho). You seem to be in a similar situation as Ziharay a couple of dozen posts up...
The E17 is a nice
portable DAC/amp, but it doesn't sound like that's a big concern for you... (correct me if I'm wrong) Depending on your budget, and if you care equally about PC/console gaming, I think you might be etter off getting a cheap ($50-60) sound card plus a much better desk amp ($100) for just a couple more bucks than the E17 alone. It covers all the bases and sets you up for a while (possibly for good, or a good long while), that is assuming you don't mind hanging in with the AX720 base for now.
Take a look at the E09k or Magni, they're not any harder to move between your PC and console unless they aren't in the same house (heck you can get an extra wall wart for the Magni for like $10). As for a sound card, a Xonar DGX will get you DH and paired with an external amp it'll sound as good as any complete solution south of $300.
The point is you end up with pieces that work well with each other, if you want an expensive DAC later for music playback on the PC you can get one, pair it with your amp, and switch between it and the DGX (for gaming). Or even get one with optical input and feed it the DGX's output. If you wanna upgrade the AX720 base later for a DSS or a Mixamp you can just drop it in and pair it with your amp... Not that you couldn't do that with the E17, but you'd end up paying for an inferior amp and a DAC you might not use much in the long run.
If PC gaming isn't a priority, well, I wrote a lot of nonsense you can ignore...
Altho I'd still go for something like the E09/Magni, tho maybe you would want to get a DSS or something like that before getting a DAC for the PC for music duties (E07 maybe, don't need to shoot higher if you have the E09).