So I just got my first amplifier and am a bit confused regarding the EQ settings. So when EQ is disabled, the frequency graph is flat, so is it setting the frequency response to flat(why would it be flat by default?) or does it just mean there are no changes being made to the default sound of my headphones? I ask because they do sound different but I am unsure if that is due to this setting or just caused by the amplifier in general since some people say they change the sound.