If jack hadn't inspected the venue, how should he know better. That is the band's manager and the venue operators job. How many times do you have to be told this. There is no evidence In your 15 minutes of research that the band ever saw the venue prior to going on stage. They may not have done a sound check if they were using the club's sound system.

The we're two parties that should have known better: the owners of the club and the manager. Both were found guilty of negligence. No member of the band was ever charged. Does that not tell you something? They were not responsible.