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Question: Increasing the volume and presence?

I am a music professor and just matched a pair of HK SoundSticks II with my MacBook. I love the clarity and cleanness of the sound, but I am wanting more volume and presence than I am getting. The Mac preferences sound control is turned all the way up and the iTunes volume is all the way up. What else can I do to get the hair-parting volume and sound that I am looking for?