i tunes vs. j river in pc realm

I own a PC and just dipped my little toe into the "computa" music server world having purchased a fairly inexpensive (but good, I think) DAC from Kingrex. Installation was a breeze and I'm listening to Pandora, LastFM and Wolfgang streams as well as purchasing tracks off I Tunes. I'm hearing that J River is an improvement over I Tunes. Can someone please explain if this ONLY comes into play during the "ripping the CD" process (which I'm not doing yet) or if it comes into play whilst just listening to the streams mentioned above. Also, what is it that J River does better?
If you get J River you no longer need to get ASIO drivers, as they come with. If you get J River 16 (in BETA, but working great) it is also a better fit with Apple ripped music, although I'd highly recommend at a minimum to use J River for ripping, and better yet dBpowerramp (which is programmed by the same company).
Srwooten - somehow Audiolab engineers disagree. Only after installing the ASIO4ALL driver and choosing the right options the volume control and the whole 'mixer' switches off.