I don't have the Zander M5 anymore. In fact, I don't have any of them, excerpt for a burn job of his M3.
There are some good points made here. The business about instruments being vastly different in Mahler's time has been made numerous times previously. However, it's always discussed as though Mahler had been satisfied with what he had heard. It has to be remembered that Mahler - at least in terms of orchestration and dynamics - was a foward looking revolutionary; not somebody trying to preserve the status quo. In this regard, Mahler was far more a kindred spirit of Bach and Berlioz, than he was of Brahms or Schubert. There's an interesting anecdote, among many, regarding Mahler rehearsing his sixth symphony. At a spot in the finale - presumably at the first or second hammer stroke - Mahler kept stopping and demanding that the trumpets play louder. Everybody in the room felt that the trumpets were already blowing their brains out. Yet, he kept demanding for more. Finally, they got it just unbelievably loud. The person who was observing this rehearsal (I forget who it was) said that the passage in question suddenly made total sense. But immediately after that, Mahler stopped them yet again and said, "good - now even louder yet". Now, here's an anecdote of my own:
I once saw Bernstein/Vienna Phil. do M5 here in San Francisco. It was tremendous performance - far more risk taking than the one that ended up on CD (performed in Frankfurt). The person that I went with was a field rep. for Polygram Records (now Universal). He kept saying to me, that hearing the VPO doing Mahler was like hearing Mahler performed on period instruments. There's some truth to that, but it's also an exaggeration. Anyway, we went backstage to meet Bernstein. Needless to say, there were many others in line to meet Bernstein as well. When we reached our turn to meet Lennie, the conversation went like this:
my friend from Polygram: "Mr. Bernstein, do you feel that performing Mahler with the Vienna Phil. is like doing original instrument Mahler?"
Bernstein thought about that for a few seconds and replied: "yes, but they play it much better in tune these days".
That little statement says everything. With the Vienna Phil., there is more of a connection to the somewhat softer sound world of yesteryear. However, today's Vienna Phil. is more of a cross between old-school VPO, and modern influences from virtually every other orchestra on the planet. In other words, hearing the VPO today isn't the same as hearing them in 1936 or earlier. In many ways, this has helped them (intonation being the biggest factor). In other respects, it has hindered them. They sometimes can sound as cold and indifferent as any other orchestra is capable of sounding. Fortunatley, that's not the norm with them.
It also has to be remembered that for all of the precise indications within Mahler's scores, Mahler once turned to his small audience (it was at a rehearsal) and said that it was the obbligation of furture conductors to make changes for the sake of clarity. That statement also tells us that Mahler was looking forwards, not backwards.
The clarinet note at bar 397 in M5/3 is one of very short duration, played in their extreme low register. I don't feel that the note is there, simply to finish the descending arpeggio that the violins are playing. If that were the case, Mahler could have simply let the violas finish it. Instead, it strikes me as a very deliberate effect. I'm not sure that it would sound any less loud with two clarinets, than with three. There's simply no other competition to be heard at that spot. However, the difference between mf (mezzo forte) and ff (double forte) is two notches (single forte being the only dynamic level between them). That would make a difference, for sure. But since the note is in their extreme low register, I don't have a problem with it being played loud, and doubled up as well. It doesn't strike me as comical.
If we were to use all first versions of Mahler's scores, that would mean a bit more percussion in the first movement in M5, and significantly more percussion in the finale of M6. It would also mean that the trombones double the horns at the "false victory parade" passage (my name for it) towards the end of the finale - shortly before the spot where the third hammerstroke is sometimes reinstated. Personally, I'd like that, and I'm not sure why Mahler chose to water down that particular passage a bit. If it were me, I'd double the horns (ff) with the trombones (forte); add tons more percussion (including three short hammerstrokes at the end of the passage), and dub in cheering crowd noises as well. For the sake of clarity, I would greatly underline what Mahler's intentions were with that passage. It's obviously what the entire, final allegro "charge" section leads up to.
Barry