Thanks! That's what i've done, but i need more diference between the spots and the music. 5db or more. There are any solution to change the mix table in windows?
Well, if you have a command-line program or an ActiveX control that changes the master volume, then it could be scheduled between music tracks and spots. Unfortunately I don't know if such thing exists.
I think it's easier to normalize your audifiles to ex. -5 db and your spots on 0db. You can use the free tool mp3 trim (see google mp3trim.exe). I do it that way and it works fine. Using an extern compressor/limiter/leveller/ultramizer you can duck the files when you set the input high enough so that the hardwareprocessor attacks. I use a use an ultradyne DSP pro 9024 from Behringer and an ultramizer on the transmitter wich makes the sound always on the same level.