During the German occupation of Czechoslovakia, Duba began to appear onstage as a guitarist with dance orchestras.
Karel Duba Ensemble was also the first Czech music group experimenting with electric guitars.
[1] A member of the ensemble and later successful songwriter and bandleader, bass guitarist Karel Vágner, even called Duba the "first Czech who played electric guitar".
They went by bus, and according to the testimony of František Živný, a founding member of the band, the chauffeur had considerable problems driving.
[3] According to this report, the brakes of the bus failed in the upper part of a hill, and it began to roll back to the left shoulder of the road, finally falling off the cliff.