There is so much that goes into a great recording.
I found the article at this link very interesting on how they used to do the recordings.
http://www.polymathperspective.com/?p=2484
It focuses on the recording techniques for orchestras, and also provides some good info on what is going on behind the scenes. Like the competition that was between Decca and EMI.
couple excerpts
“It’s not well known,” says Mike, “but there were at least seven or eight different tree formations with a variety of microphone types, and there were two philosophies of using a tree. One was the Roy Wallace philosophy which was the tree by itself, which produced a wonderful three-dimensional image; the second came from Kenneth Wilkinson who came to stereo in ’58 and decided that the tree needed help from outriggers; focusing on violins on the left, cellos on the right. Eventually their techniques blended – Wallace was using outriggers, as were other technicians.”
“Compression was something used in the pop world to get maximum dB on the tape for AM radio,” says Mike. “Decca didn’t use compression for classical recording but there was gain riding. The idea was that a loud movement would peak at zero, but the soft movements also had to come close to match. We’re not talking about ferocious gain riding, just little tweaks."