I've been using Foobar2000 for all of my music files including Flac. I've never tryed Jriver. Is it any better for play back ?
The main reason J. River and foobar sound better than iTunes is their ability to select one of the output drivers that can bypass the internal Windows mixer (WASAPI, ASIO, Kernel Streaming) and operate in system exclusive mode.
I don't think J. River necessarily has better quality playback than foobar, but it is easier for most people to customize and has some cool features.
I like that you can individually set each file resolution for either an unchanged bit perfect output, or to upsample or downsample to a particular resolution, which lets you customize it to your particular DAC's capabilities. There is an icon that turns blue when the output is bit perfect and grey when it is not. Resting your cursor over the icon displays a dialog that shows what upsampling/downsampling or other DSP options are currently in effect.
The Play Doctor and other playing queue features are very flexible and easy to use.
foobar is unable to read tags in my AIFF files so they are all placed in an unknown artist/album classifications with only the filename as the song name displayed, while J. River is able to read all of the AIFF tags.
Steve