Pros: Kinda of OK - there are much worse out there
Cons: Too much bass, treble is an assault upon my ears
Too much bass, strident treble. I guess it could be worse. Midrange is not bad. It might sound OK straight out of my out of my cheap Android phone which lacks power and sounds kind of muddy.
The treble hurts me. I wouldn't keep them though, even if someone gave them to me for free. I wouldn't give them to my kids either because I don't want to destroy their high frequency hearing.
Really ugly too.




And about the treble being an assault to ears, I don't get it too.
I can hear treble up to 18khz , so I don't think my hearing is that bad.
I'm wondering if we are listening to the same headphone. Might be a problem with your source.
You'd be happy also to have a slightly weaker bass.
Only thing that sucks is that this "corrected" edition is $350, which is how the headphone should have come in the first place. As for bass, this thing has more bass than the V-Moda M80 and Beyer DT1350. Just a tad too much for my tastes because I'm not really a basshead.
And even some sennheiser rep, said that the intent was with amperior, to reproduce same sound, with lower impedance, and improved materials. So no, it's a bad plan to get amperior, if you want improved sq, imho.
If there's a big difference between left & right then you have a defective driver.
Though, the m50s were burned in a lot more and the hd25 were fresh out of the box so I'll try again later...