None of the methods you show will allow you to fade or balance. You will only be able to adjust your sub level.
The computer control will use surround sound which means for most music you will hear nothing from the rear speakers unless you have a mode that supports this.
There was already a discussion about this elsewhere about using a specific DAC.
It will use your optical output and feed it into a fully functional converter that will allow a lot more flexibility than anything you have listed there and cost about the same or maybe slightly more.
You will have to look for it but the information within it is well worth the effort.