one further point that has not yet been raised is the angle between the
loudspeakers at the position of the listener. For stereo recorded with
crossed figure-of-eight microphones this angle should be 90 degrees. I
don't know whether present day recordings have instruments placed in
the same way, but for classical recodings that is still the convention
I believe.

I agree that the room acoustic is the most likely to interfer with the
stereo stage if the room is not acustucally 'dead' enough.

Robert