I never understood the idea that the HD800 is like an upgraded K701/702. I've heard both on many setups and don't think they sound similar at all. Maybe there's some similar categories they both excel at, but I wouldn't say it's a lock that a K701 fan is going to like the HD800. I think it's more likely an HD650 fan would like the HD800. The K701 is a more urgent sounding phone, based on what I recall about the HD800. It brings a lot of life to something like the original Judas Priest Painkiller cd. The HD800 is significantly more laid back, if memory serves. Perhaps the upgraded opinion is more specific to certain types of music sounding better on the 800.
Agreed. I've owned 2 K701's and a K702 and now own the HD800's. I love the AKG's but the tonality is in stark contrast to the Senn's. The only similarity is the large soundstage.