The HD800 is my first expensive headphones.
its really comfortable to wear it and sounds great through my Fostex HP-A8.
the treble is smoother than i first thought it would be but its still considered an bright and detailed headphone. bass is very neutral and punchy and mids is also very natural and uncoloured in my opinion.
some people may find it too bright or not enough bass when paired with the wrong amp.
the best part that i find with the hd800 is its imaging. i feel like band is playing in an nice big stage in front of me and every instrument is seperated and can be heard easily.

the Studio V is an DAP made by hisound. There are two firmware on this DAP, dynamic and BA.
I will be using the Dynamic firmware in my review and the IEM that i will be using is UM3x RC and IE80.
 
High: Really smooth high and detailed. the studio v extended the high nicely. i suspect the Studio V would not pair nicely with an bright IEM.
 
Bass: the bass is tight and punchy, its not boomy but definitely present and well controlled.
 
mids: the mids are very detailed and abit foward in my opinion. it also have an nice midrange
 
Imaging: The imaging is probably the best part of the Studio V 3rd anv. it have superb imaging making the sound like 3d.
 
soundstage: the soundstage is very wide and deep. this DAP have the widest soundstage compared to my other DAP
 
battery life: it have an very long battery life, i think around 68 hour of music playback
 
UI: The UI isnt as bad as some people say but the UI could be better (its simple to use though).
 
Special thanks to Jack also known as hisound for the promotion and a really fantastic DAP. Jack told me that the Studio V need burn in, so far i have burned in for around 29 hour. i will update my review when i notice a change in sound. i will do a comparison to the previous Studio V late when my unit is fully burned in. for this kind of quality, i think its an great value and totally worth the price.
 
edit: i forgot to mention that this player also have excellent clarity

i just bought the ie80 today to replace my old ie7. the moment i listen to the ie80 i was glad that i bought it. i tried to play an 320kbps mp3 on my ipod touch (no amp) and i hear a lot more detail than my ie7 and it also have a wider soundstage. i have burn it in for around 5 hour now and i will see whether there were improvement after 20hour. overall im very satisfied