I'm looking for a way to hookup my chromecast audio to speakers and a subwoofer (for music).  I want one of these setups (1 cast + 4.1 speakers) in each room, but am unsure of how to go about setting up the speakers.  On my home theater, the "music" mode uses the 4 surround speakers, but no sub...

I know that basic differences between analog and digital sound, but is a pc always digital sound, or does it go from digital to analog when it is output via 3.5mm cable. This leads into my next question, are 3.5mm/1/4inch connections analog or digital, or does this depend on the source they are...