Why not Deaf Leopard? Well, the band originally was called Deaf Leopard, but they thought it made them sound too punk or something. The whole thing is a little unclear to me. Why use a deaf leopard as your emblem? The leopard cannot enjoy your music. Perhaps, like the umlaut, the "leppard" lends an air of menace. It would be great if a heavy metal tribute band called itself Def Leper. However, it seems that name is already taken, and by a man of the cloth to boot.
Def Leppard definitely looks more rockin' than Deaf Leopard. It reminds me of a line in American Movie where the film director keeps pronouncing the title of his movie, Coven, as if it rhymes with "woven." He does that because it sounds more rockin' that way. An actor in the film remarks that to be pronounced that way, an umlaut should be added.
Def Leppard: 6.8