[Rhinoe]

Hello,
 
I had recently ordered a pair of Sony MDR-MA900 from Tokyo, at a reduced cost (new), and I had received them on Saturday. First, I just want to say that these headphones are incredibly comfortable and they are my first open headphones. I never want to go back to a closed design and, overall, I am extremely happy with them.
 
However, when the volume hits a certain level I noticed a strange sort of popping and the audio quality seems to be reduced. I did not have time with them on Saturday and I had limited time with them on Sunday. I also have not had a chance to play with them today, so my experience is limited thus far. My source of audio wasn't the best (Spotify premium service with high quality stream), but I have never heard it crackle like this with prior headphones. The sound card I am using, in my computer, is a Sound Blaster Z. Fortunately, for the most part, the headphones did not have issue and it is only at these increased volumes that the problems arise. Is it a defective unit?
 
They did not seem to have the same issue when connected to my iPhone, but I did not turn the volume up substantially. 
 
I am not really sure what the problem is and I am new to this. I was hoping for some input from the more knowledgeable head-fi community.

 

[Ufasas]

Got them on saturday too after 13 days of waiting. I can confirm that sound at higher windows 7 volume levels is different, smartphone doesn't let them sound too loud even on max volume, and it's fine, but on pc (i have SBZ too) at volume ~ 80 and higher i hear distortions during music playback. I am wondering if it's open back headphones thing, coz closed back ones never gave me such experience.

 

[Rhinoe]

The problem has since gone away after hooking up my magni and optical modi.