[One (M7) Q&A, Help & Troubleshooting] yoallen78:
If you're phone is still under warranty - then I'd send it back to HTC and tell them that your speakers are low.... (

YES I know it's a pain returning back to stock

(I did it 4 times to get my phone fixed by HTC) - but it was worth it ;) )

If that's not viable then nandroid backup your current phone and flash a stock rom and see if that fixes anything (if you're running AT&T - flash an AT&T stock ROM)

Otherwise ..... it might be worth a shot to edit the snd_soc_msm_2x_Fusion3_DMIC_xxxx (depends on what version of Android you're running. If you're running KitKat - then the file to edit is snd_soc_msm_2x_Fusion3_DMIC_SK) THIS MAY NOT WORK - BUT AGAIN IT'S WORTH A SHOT! I edited this file to increase the volume for my headphones and MAN DOES IT MAKE A DIFFERENCE (anything above 60% after my mods are TOO LOUD!!!).

(If you don't feel comfortable editing a file with a text editor - I'D SUGGEST SKIPPING THIS ALTOGETHER!)

NANDROID BACKUP YOUR PHONE first!!! And as a extra precaution - copy all of the snd_soc_msm_2x.... files and save them offline (or to the root of your internal SD card) in their original formats...

Use a file manager with root capabilities (FX, Root Explorer, Root Browser, ES File Explorer, etc.) and navigate to the following path:

/etc/snd_soc_msm/ - from there - you'll see a number of snd_soc_msm named files. Look for the one I listed above. COPY THIS FILE TO YOUR INTERNAL SD CARD AND THEN COPY THIS FILE TO YOUR COMPUTER (it's easier editing with Notepad++ then it is editing directly on the phone itself)

Use a text editing utility (Notepad++ works WELL and saves the file without adding an extension to it) and look for a section similar to the below (I didn't see any other sections with Speaker that had the RXx Digital Volume lines necessary to edit....)

SectionDevice

Name "Speaker Headset"

EnableSequence

'SLIM_0_RX Channels':0:Two

'RX3 MIX1 INP1':0:RX1

'RX3 MIX1 INP2':0:RX6

'RX5 MIX1 INP1':0:RX2

'RX5 MIX1 INP2':0:RX7

'RX4 DSM MUX':0:DSM_INV

'RX6 DSM MUX':0:DSM_INV

'RX3 Digital Volume':1:67

'RX4 Digital Volume':1:67

'RX5 Digital Volume':1:67

'RX6 Digital Volume':1:67

'LINEOUT1 Volume':1:0

'LINEOUT2 Volume':1:0

'LINEOUT3 Volume':1:0

'LINEOUT4 Volume':1:0

'HS AMP EN Switch':1:1

EndSequence

The four lines above in bold are the lines to edit. EDIT ONLY THE 1:67 values and increase them in small amounts (say go up by 2). So for example the new lines would look like this:

'RX3 Digital Volume':1:69

'RX4 Digital Volume':1:69

'RX5 Digital Volume':1:69

'RX6 Digital Volume':1:69

after changing the values save the file, copy the file (MAKE SURE IT HAS NO FILE EXTENSION) back to your internal SD card and use your (root enabled) file manager to copy the snd file back to /etc/snd_soc_msm/ folder. REBOOT YOUR PHONE for the changes to take effect and then see if your volume has increased.

I know that similar mods have worked for LG and Samsung devices (I know from experience - I followed similar posts here on XDA) so this may work for the One as well. If it doesn't - just revert the values back to the original values (or copy the original/unedited file back to the path listed above).

Hope this works out for you :)