Like many, I still prefer the first recording of “Einstein on the Beach”, even if it is a little short…
And one bit I’ve allways liked is “Act IV Scene 1-Building”. It’s the only Philip Glass piece that I know of that features improvisation.
It has the wonderful contrast of the Philip Glass Ensemble playing at breakneck speed with superhuman precision while the horn players play long tones leading to some free-jazz style blowing over the top.
On this recording it sounds great, especially at high volume.