I saw that the U-AMP has different jumper configurations depending on if you are using I2S or Analog Audio. What is I2S, and how does it differ from Analog Audio? Also, I would like to connect a 3.5mm headphone jack to my U-AMP, but I’ve found multiple jacks, some with 3 pins and some with 5, and I can’t find much documentation for either that would help me know which to choose or how they need to be connected to HL, HR, HG, etc. Finally, I saw something in the documentation about connecting S to Ground if headphones are not wired. How does that change if you have a headphone jack? For example, what does S get connected to, if anything?