I feel A2000X is a possible (better) upgrade if you are willing to try AD2000.
A2000X has a very balanced sound, even better than AD700, though it isn't as colored nor is the soundstage as big, but it does everything much better, otherwise.
I love how AD700 has such a quick, effortless sound and a pinch energetic, and A2000X is a lot more energetic and effortless. My sister described it as "light and fluffy". It is by no means thin-sounding. Then A2000X has great slam, very thumpy and wonderful low-end punch yet still very balanced, no extra bass. Needs a lot of burn-in, though, but in the beginning it sounds a lot like AD700, balance-wise.
This 'phone achieves a very engaging sound with it's speed, detail, and energy. It doesn't have much of a midbass hump (it is there, probably about 0.5dB, lol) or forward mids. There's some forwardness in the lower treble, but it has continued to go away with further use. Also, it has a very sweet sound like AD700, but instead of being grainy, A2000X is liquid-smooth. A little more top-end sparkle, too.
Same spaciousness as well. It feels like a cross between AD700 and RE0, yet better than both put together.
Too bad it doesn't have RE0's timbre, though.
Edit: forgot a few details.