Thank you Boo Boo for the detailed steps !
Maybe my problem (and NovaCoder too) was the use of different programs to process the audio, as far as I remember, last time I tried it I demuxed video and audio with RippIt, then I resampled the audio file with Goldwave sound editor. Maybe everything should be done with VirtualDub to work.
I will make anoter try, I hope this time it will work. I would like to convert some trailers like Aliens, Underworld and a few others. HAM6 frigging should be reduced due to colors being more dark grey/blue.