I have Toscanini's account of Sibelius 4 on a Guild two Cd set. It is a facinating reading. The maestro does depart from the written score in places. For instance he has the horns playing stopped [muted] in bars 9-11 of the slow movement and at letter G in the finale. He also doubles the woodwind with glockenspiel after letter O, bars 3-4 and 10-11. In the score, the glockenspiel is silent during these bars. But the performance is very much alive and the bonus on this Cd is Toscanini's rehearsal of the Sibelius [25th April 1940] this is a tremendous insight into the maestro's methods.-kp
Guild GHCD 2298/9