I also attended the Auckland concert and wonder what all the grumbling was about. I thoroughly enjoyed Ralph - the guitar sound did overshadow the vocals a little maybe but overall pretty good.
In the beginning the Steeleye vocals were a little lost but it improved and I thought it was a great show. It certainly wasn't too loud for me but I am over 50 and my hearing isn't 100%. I attended with an experienced musician who has played in that theatre and she thought the sound was quite acceptable.