Hej geamikoj! Aủskultu al la kanto : "Morgau" en Jutubo, estas tre bela kanto ..
Wait, hold the phone here. If Esperanto prepositions are meant to be more "literal" than in English, then why is it "Kantu al ni en Esperanto"? This sentence would imply that you are demanding someone to sing INSIDE of Esperanto.
I personally think that a better translation would be "Kantu al ni per Esperanto!". Because, well, when you sing (or speak), you use a certain language to sing (or speak), right?