I hate to burst your bubble, but I had some very close friends who were in the crew for the LA version when Michael was in it. Much of his singing was actually pre-recorded. In fact the only song he actually sang completely live was Music of the Night. Most of the other people who have done the role have used minimal recording, usually when they are rushing around backstage. Sometimes the high note for Christine is also pre-recorded. It's one of the little secrets of the show that ensures the actress can get through two shows a day.
I heard similar stories about Michael from when he did EFX in Vegas. MGM was miffed that Michael insisted on using pre-recordings for most of the songs. They didn't renew his contract and started bringing in other performers.
The cast I saw this Tuesday was actually pretty good, although there were some technical glitches during the show. I did feel bad for them because the audience was so unresponsive. No one laughed at any of the funny bits and the applause was pretty tepid.