Audio Out / Headphone Jack EQ issue

So I use my device in my car as I have an AUX input and I like to play my music, stream radio stations, or just the bluetooth for calls. My problem is, with audio such as music that is greatly affected by EQ settings, it sounds like the HTC is forcing some sort of EQ on my music. I've pressed the button on the speaker but it still sounds as though there are some things it is doing to affect my overall sound quality. Is there a way to disable this completely or turn off any bass-boost feature?

Thanks.