You do not use jRiver or iTunes with the SBTouch (although you can use them to rip/copy/load files onto the PC). You use the Squeezebox Server software on your PC. SBS can read most formats including FLAC and whatever is in your iTunes directory but you should go through the setup procedure to tell SBS where the music files are.
And, yes, you can feed the digital output of the Touch into the 840C.
More of my comments here: http://www.stereophile.com/content/logitech-squeezebox-touch-network-music-player
Kal
And, yes, you can feed the digital output of the Touch into the 840C.
More of my comments here: http://www.stereophile.com/content/logitech-squeezebox-touch-network-music-player
Kal