I heard the same spike as Sylaw. I noted it in my mini review of 6 portable headphones on my blog ( see signature). I think the 6-7 kilohertz spike can make some recordings a bit too hot and maybe even harsh, yet I also feel as Wraithape does that lower quality lossy files are most to blame.
My ear canal resonance also happens to coincide with this peak and unfortunately equalization is probably the only way to tame it and not affect the other frequencies too much. I use equalizer on my idevice to set a parametric notch to control a spike like this and use it to very good effect with my Vsonic iems. Check my blog for details on how I use it.
i think i hear that as well, i'm not even sure its the files or what it is but it does sound a bit "brash" sometimes, thats the only word i can describe it. but for the most part the treble is very impressive