[MPlayer-users] Need help for proper downmixing

[Nico Sabbi]

Hi,
usually when I listen a 6 channel ac3 track in my earset I can hear only 
whispers;
-af volnorm amplifies sound quite well,  but isn't perfect yet.

Using -channels 2 always plays sound too low, so I replaced it with 
-channels 6.

If I use
-channels 6 -af hrtf=s -ao pcm:file=x.wav

sound is exactly how I like it, but the resulting audio stream still has 
6 channels,
although I verified that if I play it with -channels 2 it still sounds 
correctly.

In order to amplify and downmix the original ac3 in a single pass  I tried:

-channels 6 -af hrtf=s,channels=2                               - there 
are still 6 channels
-channels 6 -af-adv force=3,list=hrtf=s,channels=2  - audio is 
accelerated (2~3 x)

So, how should I insert filters?

Thanks,
       Nico