A handicap is that to be able to install Dee you need to have WinAmp installed on your PC.
Edited: see this post.
BSPlayer supports WinAmp2 DSP plugins, but you can also e.g. use
dedynamic filter. (Don't use that myself at present as its use is causing errors in build 808.)
At present I (i.a.) use WinAmp2 DSP plugin
'Enhancer 0.17'. Another WinAmp plugin is
'Compressor & Wider 1.1'.
Further plugins (incl. '
Dee'-versions) can e.g. be found
here.
Also have a look at
this post and
this post.
There are also other possibilities: e.g. if it's AC3 sound you can use "Gains"and/or "Equalizer" possibilities of
AC3 filter ([Start] > Programs > AC3filter > AC3Filter config). As I don't use ffdshow myself, I don't know for sure, but I thought it also offers a possibility to increase volume.
