Discussion about the Korg PolySix synthesizer

Andy can you clarify why the NJR4560 is swapped out for TL072P? I see that there are other 4560s out there that are available, though perhaps something in the specs makes it incompatible. Of hand here one form Mouser:

http://ca.mouser.com/ProductDetail/NJR/NJM4560D/?qs=sGAEpiMZZMtCHixnSjNA6EIiaWUSjOTKRvX1zNG7jh4%3d