Any help for a new guy?

I'm going to preface this with saying that this is my first pair of higher-end headphones, though I've used many others before, I've never owned a pair myself. So I was meaning to upgrade my audio since my previous pair of in-ears had gone missing. I searched around and the AKG K172 pair seemed like the pair for me. For the most part, I LOVE these headphones. (Sometimes they don't have that earth-shaking feel from the bass that I'd like for songs like "Vulkan Alarm!" by ZZT, but that's solved with a bit of temporarily changed EQ settings.) My only uneasiness is that I get a bit of distortion at certain, higher volume points when using them directly with my computer. I've found that, for iTunes, this is solved by going in to the equalizer, turning on flat, turning the pre-amp down, and just turning the volume up, but sometimes I still feel like I'm getting not quite as true sound as it can give me. I've worked with plenty of different monitoring speakers since I'm learning music production, so I've gotten a sense of pretty "true" sounding audio, so it's weird to me how certain, more trebly sounds don't seem quite right. I can't say I fully know what I'm doing, but most of my music is .m4a or .wav. I don't turn it up to 11. Any ideas/tips? Anything would be appreciated.

Hmm... Anything else? I mean, for the most part, these are great. It's just these specific, small cases that I'm just wondering if I might being doing something wrong or if there's a simple fix to them. It's just sounds like the OS X trebly volume click gets distorted at higher volumes or Spotify just sounds a little off on certain songs.