Hmmmm. Doesn't sound German - but "Gaudeamus Igitur" is usually identified as a German drinking song; and "Kyrie Eleison" as an integral part of the Latin Mass....
I'll keep looking for it. I think I've seen it somewhere. From what I've found so far, apparently it was sung by Enrico Caruso in 1902, from Act 1 of the opera Germania, by Franchetti.
There's a YouTube recording here (click).
Any chance you can post the Italian text?
-Joe-