Sound hardly audible

I am a newcomer to Linux,and used to paly cd either from my dvd or my cd-Rw under windows.
My sound card is connected to my hifi amplfier thru the Amplifier Aux input.
Under Linux I have to turn the Volume knob almost to the maximum on the amplifier (level 34 on a scale of 40) although under windows a level of 7 is pretty loud.
I suspect that I have to customize something somewhere, but what, where and how?

You could try turning up the volume using KMix under Multemedia -> Sounds.

thank you. That was a stupid question.