Was searching to find a solution to this. Came across the bug report, then came across a blog post that got rid of my "hisstle." Don't know if it will be of any help for you, but under Alsamixer I turned off the "capture" volume (after pressing f5) and this got rid of the hiss at volumes lower than max.
http://johnsunixtips.blogspot.com/2011/01/check-if-speakers-are- working.html?showComment=1303257219144#c4155961302649813612 -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/641479 Title: Surround Sound hisstles (hiss + whistle) when the volume is changed -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
