I definitely take your continuous hate towards Sennheiser headphones into consideration. 

  We could have different tastes... But if you say that they dont measure and sound as technically great as HD800, its all quite clear.

  I've owned a DAC with the same chip, StageDAC... And it quite does influence sound if you pay attention and know how to listen (soundstage, imaging, basic tonality very slightly).

  I would rather go Vali/Modi for Q701... Probably better synergy.

  Audio-GD 15.32 is a briliant option! You will love the way you can customise DACs performance using different oversampling and filter options :-) You basically cannot be unhappy because you can make the DAC sound warmer or more detailed depending on your taste or audio chain...

  If on budget, I would definitely go with a warmer amplifier... A good DAC for the price and a bit warmer SS amplifier like M-stage.

  I am also a headphone kind of guy myself... I just enjoy exploring the world of headphones rather than nitpicking differences among amplifiers or DACs (though some differences are of course present).   I would expect the PSU to make some difference, not sure how big... It depends on many...

  That's a tricky question... I personally find K712 Pro slightly on the warmer side but their emphasis around 2khz makes vocals a bit shouty with dead-neutral or brighter SS amplifiers. I would say that K712 Pro can work very well with almost any amplifier but I would basically recommend some...

  Well, both HE-500 and K712 Pro are among the very best I would recommend you to get...   Up to 500USD, definitely go for K712 Pro if you ask me. But if you can go higher, I would recommend to go with LCD-2 Bamboo (today for 796USD). LCD-2 are technically better than both K712 Pro and even...

  Ive heard both on the same setup and it really depends... I would say that K712 Pro are the better value.   HE-500 are amazing for their very natural frequency response... And they have that orthodynamic transparency. On the other hand, they are not technically that much impressive. They...

  Yeah, I've never said Concero is not a great DAC... But its noise filtering is not very good. There are plenty of DACs with extremely good USB implementation - Matrix X-sabre, Yulong DA8 or Ciúnas DAC are the ones I found interesting myself.

  Best up to the price of HD800? Well, HD800, or some very well done DIY electrostats...

My opinion is that you should go with AKG Q701 if you want the best experience with classical music - good frequency response and the best soundstage for the price. You will find both pretty much welcome. DT880 are also a good choice especially considering their superior bass response (deeper) -...

  If you hear differences among USB cables, blame your DAC (or Audio PC) for not having at least good noise filtering... In other words, you should definitely change your DAC to a better one.   EDIT: I see you use Concero... That explains everything.

    I definitely agree... 800USD for a brand new LCD-2 is a great move, better than 700USD for HE-500 IMHO (LCD-2 are technically higher, no doubt about that + they are easier to drive well). The problem is that you could dislike its closed-in soundstage and a bit fuzzy imaging... That's...