The HTC One (M8) comes with front-facing BoomSound stereo speakers and a dedicated headphone amp to deliver unmatched audio quality. HTC states that the front-facing speakers on the One are up to 25% louder than its predecessor while delivering cleaner audio output.
Reviews of the handset also suggest the same with GSMArena stating that the One’s audio output is among the best in the business. However, there will always be a bunch of people who would like to increase the headphone and speaker volume further. Keeping this category of people in mind, XDA member v-b-n has released a mod that increases both volume outputs on the One (M8) by up to 150%.
Root access with a custom recovery is a must since the mod tweaks some stock system files. The developer has also provided a flashable zip file to restore back to the original files just in case you don’t like the end result.
If you are among the selected few who wished that their One (M8) could deliver slightly louder audio output, head over to this XDA thread for the download link to the mod.