Interesting find.
I went into a store Saturday and had my 3D replaced, Green tint with some pictures.
My replacement device was nice and loud. I immediately went to my office. Put it on the charger, started to DL my apps. By the way after i signed in using my gmail acct, went in and accepted terms of Market Place. I noticed all my apps were automatically downloading. Thats a frist for me.
Ok that wasnt realy why i am posting here. Some of my apps are streaming media. One of them is a police / fire scanner app. I actually provide some feeds so i test it to make sure they sound good. Well the audio was louder then my previous EVO 3D. I thought yes great. I am happy.
An hour or two pass, then i get a notification for a maintence update from HTC. I down load it, 26 megs. Same one that came out to address the issues of calendar i think.
After reboot my scanner app is no longer loud. Its back to being quiet.
Tested out music and Pandora, same. So my GUESS is that something in that maintenence release that first came out is also lowering external audio.
Great way to test this, start the Spiderman 3D game. Its audio is pretty loud on start up.
Just an observation i made this weekend.