Well my nad hp50 arrived today, pretty quick from denmark warehouse.
The headphone is actually not as large as i feared it might be. Although the cups dont really want to stay folded and the cable is flimsier than i thought it would be and i dont like that you dont get a tactical click when you volume up or down.
The sound is quite nice albeit a bit thinner then i thought it would be, i thought treble might be too muted for me but it i snot. Bass is also quite good.
Soundstage is very nice for a closed can.
I think these are just more neutral then what i am used to.
These have ample volume with y iphone 4.
I am a bit afraid of how much these might leak sound though. I dont listen at that loud volumes but hwen i have these in my hands with music playing i still can hear it. I will have to ask someone to listen for it when i have these on my head.
I am still curious how i might like the momentums overears so i might have to get these to compare but i would have to send one of them back.
Perhaps the momentums sound would be a bit warmer/fuller more exciting?
As for DAC/amp - you dont really one. They are easy to drive and will sound just fine off an iPod Touch.