Very loud USB speakers

I recently bought a pair of Logitech S-150 speakers for my MacBook. They work fine, except I can't adjust the volume to normal levels. At the lowest system setting, one bar, the Logitech speakers sound as loud as my MacBook's speaker near its maximum volume.

I looked at the settings in the MIDI Audio Setup application and it shows that at the lowest system setting, one bar, the output is 17dB. The maximum level is 67 dB I think. This is for the Logitech Speakers. Above around 40dB the speaker volume doesn't change, so it's clear OS X Lion has an incorrect range for the speakers. For my MacBook's speakers, the range goes from -64dB to 0dB.

My question is, is there any way were I can change the range for the speakers? I want something around -20dB to say 20dB. I've looked all over the MacRumor forums and Apple's discussion boards. The Logitech website has no information and just says that drivers aren't required for the speakers. I'm thinking this is a OS X problem. Right now my solution is to manually enter a dB value for the left and right speakers each time I want to change the volume. If I use the keyboard volume controls then my options are LOUD or mute.

Thanks!