The solution is actually really simple: delete the system app DSP Manager. Seriously. Do that and reboot the phone. Bam, clear audio through the headset jack at full volume again. Thanks XDA Forums for the solution.
HTC Hero Android Phone (Sprint)
The personal blog of a computer enthusiast and Gamer.
Sitting outside listening to a dj cycle through this collection of mixes. Earlier in the night he played the song that I dedicate yearly to my friends. At least the ones that were lost. Keep playing the music dj, I know everyone can use right now.
Heavy rain and winds for a good portion of the night. All is quiet right now, but more thunder storms heading this way.