Help with Restaurant - volume

Hi all

I'm owner of a small restaurant and I purchased a 16gb ipod nano to play songs purchased on iTunes (I have paid all license fees, etc).

The issue I have is that the range of artists is wide, in genre and in time. mostly blues, rock and funk but varying from the 60's to the 90's.

Unfortunately songs play out at very different volumes, to the point where it notices and customers express a negative reaction.

Is there a way to get all songs on an iPod nano to play at the exact same volume? I have tried using sound check in settings but it hasn't helped.

Or is there another player I should be using?

Thanks

J