Sure. Select all the audio clips and use Modify - Levels. You can use the shortcut CONTROL-] to raise 3dBs and CONTROL-= for 1dB, but I personally prefer keying in the right number because sometimes the results of using shortcuts for audio levels and panning aren't immediately visible.
A second way is to use the Audio Mixer under Tools to raise the Master Volume. I'm not a big fan of this method, though.