post your signal-xenial.list. there shouldn't ever be the word sudo in your sources.list
Code:
deb http://ppa.launchpad.net/team-xbmc/ppa/ubuntu xenial main
the address you are targetting should be different but the above is the right way to have a source list entry. if you are doing source code instead of binaries you should have the same line but beginning with
instead of deb.