I can spend ~ $500 if I return the O2 (arrived with deformed case), or ~ $300 if I keep the O2.
I keep coming back to the AD700 because it sounds easy, laid back, and normal. The Q701 sounds good but it not nearly as peaceful as the AD700.
I have considered the HD 650 but it is very expensive at $500. The AD900x interests me, but after reading this comparison between the AD900x and the MA900, I think that I would like the MA900 more. (AD900x is $280, MA900 is $205)
What do you mean by "peaceful"? The AD700 is a nice $100 can, but it does not hold a candle to the Q 701 in any area, except efficiency. The AD700 is almost devoid of bass (and I am NOT a basshead of any stripe). Compared to the Q701, which many don't like because it has too little bass, the Q701 is almost a basshead can, standing next to the AD-700.
My guess is that you just don't like the sound signature of the Q701--probably due to the way it pulls apart each musical voice.