after 3 sessions (couple of hours each) now comparing the 2, the k1000 is a headphone that to me is in a class of its own.
The HD800 is a great headphone, a flagship product at that, the senn engineers have done a fantastic job of getting rid of that crappy hd650 veil, its gone!!!!!! (i removed both foam bits from the earcups to get around it but some persists)
it resolves well, sounds great and if someone had never listened to a K1000, would sit up there in pure quality of sound delivery. i would love to own one, it does a fantastic job when compared to the 650, no question about it..AND it begs to be run balanced, this is a serious option to consider/factor in.....(i am speaking in a relativistic sense having run the k1k balanced and common ground)
i have some hard decisions to make, its this or that awesome Manly Stingray. boy did the K1000 sound lusciously accurate, gorgeous, stupendous soundstage.... i will gladly buy another k1000 if i ever got the opportunity. these things are awesome, the only thing that would improve it would be a 2 driver concept where the other driver handles bass and bass alone. i think that is what akg should be aiming for, there ain't anything wrong with the everything else that the k1000 does, maybe we will see a 2 driver earspeaker, with the bass one surrounding/projecting around the inner driver...
(i used a dac1 with a wadia/denon/arcam transport)
k1000 was run balanced from dac1 outs and unbalanced from my sr71, lehmann black cube, hd 800 non balanced all along from all 3 options.
paulmac 3000 feet high
black hawk down soundtrack
Secret Garden (various)
Rachmaninov (various iterations of the 2 & 3 piano concerto)
Heifetz, Rabin, Oistrakh, Kreisler, Menuhin (various pieces)
Rostropovich, Jacqueline du Pre, Casals, Fournier (bach cello suites)
Nusrat Fateh Ali Khan