The only problem with this excellent app is that Plantronics, after buying out the author, simply shut down development of it, for no apparent reason. WTF is the point of buying something that IN NO WAY IS IN COMPETITION WITH YOUR OWN PRODUCT and then discontinuing it?
Volume logic can be hacked to make it work with Snow Leopard, but the hack, IME, with keep VL alive for only thirty days. After that, it's dead again. Perhaps it can be re-hacked, but I haven't tried to do that, yet.
And GenAudio, after buying out AstoundStereo, apparently has the same plan for AstoundSound, which hasn't been updated in years. It still works, but only after you restart System Prefs, a sure sign of approaching death.