[SubDub]

Good Day!

So I received a pair of Beyerdynamic DT880 (600Ohm - Version) yesterday.
I was really exited about them, so I hooked them right up with my DIY amb M^3 to give it a listen.
Oddly the right channel was dead. I concluded the headphones were faulty, since the right channel didn't play either when I
switched sources to my iPhone 4.
After that I gave it a final try by connecting it with the M^3 headphone amp again und turning up the volumen to a quite loud listening level.
And there it was: The right Channel kicked in and everything seemed fine (even at low volume). After 5 minutes of listening I retried my iPhone 4 as source and the right channel
actually worked this time, too. My guess at that time was that there was a initial problem with the right can that just needed a bit of a bumb in terms of 
sound output to be solved.
After leaving them alone for a couple of hours the same problem occured again and now I'm not sure whether
that's a normal phenomenon with high-impedance headphones that I never heard of (I'm very new to this subject ) or my
DT880 are faulty.
 
 
Any thoughts are well appreciated!
 
 
Thanks
 
 
EDIT:

Nevermind - Now the right channel is dead whatsoever...

I'll return them.