If you are not going to use the DAC section of both amp, I don't think you should limit your choice on just these two. I have put at least 24 hours on D-zero now and my original impression still stands - I find D-zero a bit on the bright side and just a tiny bit grainy / edgy on the top. Personally I won't pair D-zero with already bright headphone which might causes sibilance. Also, while the width of soundstage is excellent, the depth / layering is not quite as good. Overall I'll say D-zero is still better than E7, but for the same price range, there are other choices as well. E6 (which is better sounding than E7) is IMO roughly on par with D-zero on the amp section - not quite as wide on soundstage, but better on depth and more texture on the mid / low. E11, like E6, not quite as wide on soundstage, but better on depth and more texture on the mid / low, much better on layering. iBasso T3 / T3D is also good choice, roughly on par of E11 and better than D-zero. If you are willing spend up to $150, LEAR FSM-01 (found on eBay) is pretty much better than both T3D and E11, but it is also also a little edgy like D-zero and might not go quite as well with really bright headphone.
As I have said before, I think the real value on D-zero is on its DAC section. It is by far the best sounding [PCM270x + WM8740] combo I have heard.
I guess I am one of very few who have both D-zero and E10 right now. If you don't need portability, I'll recommend E10 over D-zero. E10 is cheaper (around $80 or so), the amp section is much more powerful and better textured, the DAC section is better (slightly more detail + 24/96 support). The only place D-zero outshines E10 is on soundstage width. If you need portability however, D-zero is still a really good choice at the sub-$150 bucket.