Almost desperate on rsync from macbook to NAS

[Boniforti Flavio]

Hello list.

I'm almost getting exhausted, thus I have to bother you people to get some help.

I simply want to sync my "iTunes Music" folder from my MacBook over to my NAS.
The scenario is like this:

source path: "/Users/bonny/Music/iTunes/iTunes Music/" (in here there
are all the subfolders I want to sync over to the NAS);
destination: "rsync://root@192.168.1.100/musica/iTunes Music/"

What I did is to copy the stuff over "by hand" (tens of GB!!!)... now
I sometimes add new music to my iTunes Library, therefore I don't want
to sync all stuff, just add to the NAS what's been added on my MacBook
and delete on the NAS what has gone from my MacBook.

I tried many many ways, but without any success!!

I tried to play around with trailing slashes, but I got tired while
not succeeding :-/

My best guess is following:

rsync -ahzv --delete --progress --numeric-ids --ignore-errors
"/Users/bonny/Music/iTunes Music"
"rsync://root@192.168.1.100/musica/iTunes Music"

I'd leave *both* paths *without* trailing slash... is this OK?

Please anymbody help me in getting things working, I don't want to do
everything again from the beginning (rsyncing from zero)...

Thanks,
Flavio.