[DCofficehack]

So I just received a pair of used DT880s/600 Ohms. My amp hasn't arrived yet, but I was curious and plugged it into my MacBook Pro. Yes, you can hear it, but it could clearly benefit from a boost. So I opened up the Equalizer and put the pre-amp thingy up to the maximum position. And played some of my favorite ALAC music. What I heard in the higher registers--in the left ear--was bad. I guess you can describe it as flutter, but what it amounted to was an inability to handle those frequencies.  Not something I encounter with my IEMs and DT770s. I put the pre-amp back down to the middle position and also tried just turning the equalizer off, and the bad sound went away.
 
So, are my cans busted, or might it be something to do with the iTunes amp? I'm curious about what I'll hear when my amp comes in...
 
Ps. The sound otherwise is fantastic. Janos Starker doing Bach cello suites...wow, there's a little extra something there that's not present with the 770s. A bit more of the sonority of the instrument. I like!

 

[MindsMirror]

It is called clipping. When the digital audio already is at 0dBFS (100% volume, as loud as it can go), and you try to make it even louder with software, the tops of the waves get clipped off which causes distortion. It won't have damaged anything. Your amp should have enough gain that it can increase the volume without clipping or distorting.

 

[DCofficehack]

Thanks. I did some reading about gain and clipping, and I think your diagnosis is correct. I hope it is. I want this purchase to work out.

 

[DCofficehack]

Amp came. Sound is sublime.