I can't specifically tell you about JRiver for Mac, but I am currently trialling it with Windows and I can say, without a shadow of a doubt, it's far and away a better sound than iTunes. I have just compared Windows Media Player, iTunes and Winamp against it and they all sound different, my order of preference being as I've written them above, WMA worst. However, you also need to optimise set-up: JRiver has the capability to run using ASIO drivers, the others use Direct Sound, giving, to me, a glassier sound, while Winamp sounds best using Waveout. Sorry, none of this useful for Mac maybe, but may help others; regardless, JRiver runs at the highest bit-rate possible on your machine, downconverting only when necessary. The sound is the only one that sounds like real high end hi-fi. I am sad to say that I am going to have to splash out $50 and buy it, its that much better than all the free rivals. Its a 30 day free trial, so you've nothing to lose deciding for yourself. Its library and display handling capabilities are more comprehensive too, as a bonus.