I mentioned
AstoundStereo in another thread but I think that it deserves one of its own...
AstoundStereo is a software solution for improving the sound of headphones and small speakers. It has a thirty day free demo and is on sale through May 31 for 50% off. It is available in Mac and Windows flavors.
I'm so impressed with the audio improvement that I registered the software. I've always considered my Bose speakers and bass module to have first-class sound when it comes to computer sound systems. But AstoundStereo impresses me with its sound expansion technology; I tried to emulate the effect using the iTunes equalizer but I was unsuccessful. (AstoundStereo is available system-wide on a Mac; it isn't linked to the audio source.) And there is a bonus feature: If you use an Airport Express and Airfoil to stream audio to another sound system the AstoundStereo effect will be heard on the remote system.
I'm not the only person who likes AstoundStereo; I found 2-3 online reviews that gave it two thumbs up (or at least the digital equivalent...) Apparently AstoundStereo used some sophisticated voodoo to do what it goes...
Anyhoo, the proof is in the listening, isn't it?
Enjoy!