This is clearly not going to be an uncontroversial review.....especially give the reviewer's stance on external dacs/amps in a couple of threads.
 
All I'll say though is that at the time I also tried a conductor with the HD-800 and compared it with the way my V200 sounded.  I have to give it to you:  your observations about a cold, brittle/analytical sound match what I heard at the time.  It may technically be a good product (fast, resolving, all you want) but it certainly didn't sound like a good combo with the HD-800 to me, those cans benefited by being taken down a couple of notches by a slightly less resolving and warmer voiced V200 and imo and to my ears they really do well with a good tube amp.
 
Not going to get into the objective/subjective debate but imo very few people -even those who claim the contrary- want a truly objective sounding dac/amp combo.

Just giving my honest perceptions, whatever they're worth.

ag8908: I always have to give a thumbs up when the OP tells it like it is on a piece if equipment that is thought by some to be the holy grail of headphone amplification.. I am sure that this is a fine piece of equipment  to some, but not for all. If I spent that much money and was told to let it warm up for days ... I think I would be looking for a refund. I am looking for enjoyment. I am not looking to listen on someone elses schedule.

Having audible noise in line-out is a faulty behavior. Either something else is wrong in the setup or you've got a faulty unit. I'd suggest contact the seller for troubleshoot or even exchange/refund/etc.