Beats audio is not present in the new HTC One M8, however HTC has recently released a Harman/Kardon Edition of the M8. This device does not differ from the original released version in any hardware specifications. The only difference is a software enhancement which restores lost frequencies that you get in compressed or streaming audio. With the H/K changes being only software it was easy enough for developers to create the modification to change your M8 into an H/K version. Developer "baadnewz" has developed the mod that will work on any variant M8. If your device is running a GPE rom you will need to first flash to a Sense based Rom before this mod will work. Head to the link below for the downloads.
Via XDA