Remember I was typing before I'd seen everything you meant :D
However, I still think the statement is far too generic, like music itself, it is open to interpretation.
I read it as
"Absolutely EVERYTHING you (anyone) need to know about music (all music, music in general) is in the sound"
I certainly won't know about the potential emotional power of a piece if it doesn't actually move me, it doesn't mean the potential isn't there though, and I need to discuss with others to unlock it - I need to learn and know something externally before I can appreciate the music fully. But on the other hand, perhaps I don't "need" to appreciate it fully...
Also (bearing in mind how I read the statement), I might "need" to know who wrote it and when they wrote it, and how it was recorded, or if it is a live performance, what make of bow is 3rd violin playing with, etc, etc...
But taking your meaning of the statement, yeah, I can agree with most of your stuff.
Except the "Hear sound + experiment = find way to match sound" :lol:. Unless you're further restricting the statement to a piece of music where I "know" exactly what the instruments are already (ie I know of their existance and what they sound like) then the experimentation will involve, um, obtaining knowledge that is not inherent in the sound itself...
EDIT: Gonna have to go soon - but I do hope you appreciate that I think this actually a pretty good thread, and nice one for starting it in this open ended fashion :D