I own an alesis dm6 mod. how upgrated firmware?

Have you updated the firmware recently? If not, do so.
If you are having volume issues, you can adjust them with the following:
Adjusting the volume of individual pads:
-Press Voice.
-Then press Volume.
-Strike the pad you would like to adjust.
-Then use the + and - buttons to adjust the volume of the individual pad.
-To adjust another pad, strike that pad, and repeat step 4 above.

No, it will work for some time, but will eventually overheat and cause damage. Spend the $10-20 and have piece of mind.

The amplifier may be turned up too high!

MAKE SURE WHEN YOU ADJUST THE VOLUME YOU PRESS
SAVE , GO BACK IN A CHECK VOLUME LEVEL TO A MAX OF 16

There's a tiny switch on the back of the module "kick type" try switching that

it going to senser problem open clean and try

It appears that you have to select a "Kit" of drums when using the external triggers. It appears that the volume level for the kit and that for each voice MAY all have to be set, especially after new firmware download. Read manual about KIT volume level and selecting voice and volume level for those. Manual is NOT very clear about these things and you have to try them as this is where the probllem is.

you have a bad cable (wire) or a bad jack (where you plug in your earphones) plug your output into another device (guitar amp for example) and see if the problem persists. if it does then it is most likely internal problems with the output jack. If this is the case you will have to take the unit apart to find out where the problem is. if you're not comfortable doing this then you will have to take the unit to someone who is.

Two things:

Check that cables are seated, especially the one at the main module.

Second, look for a setting for "Local Control" in your user's manual; That setting should be "On" to accept the triggers from the pads.

I think your best solution is this> You can add 10 more triggers with it:http://www.alesis.com/triggerio