sound on mac pro

[Arzan]

Hi guys, sorry fedora/linux newbie here, I was finally able to get  
fedora 8 running on my mac pro, I don't know if this would be the  
right place to ask this question but here goes, for some reason the  
volume of my sound under fedora is really low I have all the sound  
sliders turned all the way up, even with my headphones on I can  
barely hear it, I mean the main tower speaker is out of the question.  
I know its not a problem with my sound card as it works like a charm  
under os x and XP. Any suggestions on how to fix this please.

thanks
Sam