I was at the Baltimore show too, and there certainly were problems, but as
you suggest, my impression was that the sound system was at fault. Any time
MT/HH spoke louder than a normal speaking voice, everything blurred together
and it was very hard to distinguish words _ even for me, and I knew what he
was saying. People who weren't very, very familiar with the material must
have been lost much of the time.
Just as an aside, I did think it was the weakest of the four shows I've seen
(the first in 1977), from a content standpoint. Probably because the 2004
election was looming (this was in early May), Holbrook relied heavily on
Twain's political commentary, which to my mind is generally not as strong or
distinctive as his other writings.
But I'd never experienced any problems of this kind at any of his shows, so
I assume the difficulties were technical in nature.