There's no equalizer on board. You have the option to toggle Boomsound audio on or off with the headphones on. You cannot disable the feature when playing through the speakers.
Strangely enough only one of the HTC One (M8) units we got to play with turned out to have a built-in FM radio. The European version comes with an FM Radio receiver and an FM radio preinstalled, while the Verizon unit lacked an app. It's anyone's guess whether the hardware is still there and has been disabled (meaning that it can be unlocked with some sort of mod) or if it's gone altogether.