Recently I have been to a concert, where Carmina Burana was presented. It was my first time hearing a live performance of this masterpiece. However, I have found out that live performance differed greatly from what I was used to when listening to the recording. In certain parts I could barely hear the performers over an orchestra (most notably Estuans interius, but even choir in In taberna quando sumus was problematic), making it a sub-par experience. My friend confirmed that she could barely hear the singers in some parts as well. As far as I can tell no microphones were used. I do not recall having this problems when attending another performances in other places, e.g. operas, where microphone support was not used as well.
I know next to nothing when it comes to music practice or theory hence my question: what could be the cause for such sub-par experience? Could it be the poor acoustics of the building? Or maybe I was just used to the studio performance of the work?