I am not sure either Nepathya asked for such venue or organizer choose that but its complete wrong place for concert. who likes to watch concert staying in Opera Theater ?
I heard about Amrit Grg asking organizer not to take them to public place last year.
Ballroom, where Bipul Chhetri perform last year was perfect venue. Good for DJ too. I met one organizer (on fb page) and ask him if there is any DJ session after concert and he said yes. but turns out they screw it.