Logitech Headphone sound is faint

My Logitec USB headphone sound is just barely audible on my RHEL Workstation OS even with the output set up to full (150%/10.57dB). The same headphones work fine in a WinXP Pro virtual machine guest on my RHEL host (through VMWare). It also works fine when I boot the machine into my native Win 7 Pro. So, does anyone have any ideas on how I might fix this?

Thank you.