I was sitting on the wall dead center behind the floor.
Overall, I'd say the sound quality was one or the worst I'd heard at the Palladium. I've seen Opeth 8 times now, and I would say this sound was the worst of the 8. I found it difficult to pick out the melody, and I know all of the songs they played so it should have been easy. The mosh pit was crazy - something i would never do.
Nachtmystium - I had never heard of them before. Pretty basic stuff, although I thought the last song they played was excellent.
High On Fire - good energy for a 3 piece band. I only previously knew the song Devolution, and they kicked ass playing it live.
Opeth - aside from what I considered poor sound quality, they were excellent as usual. Heir Apparent is tied for my all time favorite song (by any band) along with Ghost of Perdition (wish they played it) and The Drapery Falls. Their set list was an interesting mix. Mikael interacts great with the crowd, and they are just plain solid on stage. After 8 times, I still can only say that I think they should play The Funeral Portrait - it will probably so down as the one song I always wanted to but will never hear live.