Liederjan did a Yiddish album? You sure you aren't thinking of Zupfgeigenhansel? Both bands have recorded (or did record, in the Zupfis' case) many marvellous albums.

There are other artists, many of them less well known, who are excellent nevertheless. Christof Staehlin is one of my favourites, with a breathtaking way with the German language. Dragseth Duo are another, singing mainly in Low German though they have turned to English in recent years and are doing a nice version of 'Sailing to Philadelphia'.