Alsa Volume Boost
To be described step by step
http://igmrlm.blogspot.it/2012/06/how-to-add-pre-amp-and-increase-maximum.html
http://alsa.opensrc.org/How_to_use_softvol_to_control_the_master_volume
To be described step by step
http://igmrlm.blogspot.it/2012/06/how-to-add-pre-amp-and-increase-maximum.html
http://alsa.opensrc.org/How_to_use_softvol_to_control_the_master_volume