The level indicator in the screenshot does jump around even if nothing is playing. The indicator also reasonably represents sound levels when music is playing. I dont have any mediaservers running or noisy browsertabs open. Also no mic connected. When I turn the volume to max in software and on the amp, there is no noise from the speakers at all. Played music is loud and not distorted. Hardware: Realtek ALC889 over optical audio connector to a generic amp. Software: Debian Wheezy with latest backport kernel 3.14 (same thing on wheezy 3.2 stock), wheezy pulseaudio, xfce session, a custom asound.conf that enables pulseaudio to push sound over optical port. /etc/asound.conf pcm.a52 { @args [CARD] @args.CARD { type string } type rate slave { pcm { type a52 bitrate 448 channels 6 card $CARD } rate 48000 #required somehow, otherwise nothing happens in PulseAudio } }