Silencing sounds on the S4 is not as easy as it seems.
For stock Rom and even on custom roms (at least TW roms, which retain Samsung features) using the blocking app and turning off notifications frequently does not apply or "catch" some apps that seem to sound off in spite of the silencing measures.
When you (or, worse, your better half) hears a sound in the middle of the night after running through the normal muting functions or routines, then it is necessary to identify the offending app, open it up and get into its settings and ensure it has no notification sounds. (It's not enough to go into app management and turn off notifications for that app!!)
As to the start up sound muting, well the rooting/ changing file name is good; also many custom roms don't have startup sounds; and finally you might try to turn off the volume when you are sitting down and see if that holds for the next restart (but I am not sure that will work...)
Posted via Android Central App