David Lai I clearly hear the hiss through headphones. You're not at all wrong. Your recording isn't a pathological case, either. It's definitely something that would come up in use.
I'm puzzled as to why it's so bad. Presumably, as we've both speculated, the additional mic samples were recorded during the same session as what made it into the original Ivory II ACD. What's different about the additional perspectives? Interestingly, the further away the mics, the worse the hiss.
It's almost like they recorded the additional mics at reduced volume as part of a planned overall mix for the original Ivory II ACD (rather than as separate, mixable perspectives), then scrapped that idea for the final release (as the default perspective of Ivory III ACD is identical to how my copy of Ivory II ACD sounds). And now they've resurrected those original recordings but have had to boost the amplitude to make them usable as separate perspectives.
Obviously, this is pure speculation. I've got basically nothing to base any of this on. It's just throwing something at the wall to try to explain what I'm hearing.