Hello Atugores,
Just to clarify, the guide only suggests a very, very rough rule of thumb to give an approximate idea of likely static polyphony:
As a very, very rough rule-of-thumb guide to the approximate static polyphony in simultaneous pipes that can normally be expected with recent multi-core Intel processors with a good-quality audio interface and
a 64-bit operating system, subtract one from the number of CPU cores then multiply the result by 1200-2500.
Likewise for the static polyphony figures that different types of instruments might need:
As a very, very rough guide, we would recommend that for average use ...
Note also that the computing power needed (and thus static polyphony) depends a lot on how you play. For example, if you often play very fast on very wet surround sample sets with lots of stops drawn then you may want significantly more polyphony than those suggested rough 'average use' guide figures.
Looking at Apple's website and prices, if I was buying a current 27-inch iMac for Hauptwerk use, my personal inclination would be to go for their fast CPU option (the quad-core 4.0 GHz i7), since that's likely to give significantly more performance (probably 25-40% more polyphony) than their CPU base option (the quad-core 3.2 GHz i5) whilst the price difference is fairly small, relative to the overall price of the computer. iMac CPUs can't be upgraded later, so I feel it's worth building in some 'future-proofing' (and also to be certain that you have ample CPU power now) where it's possible to do that without excessive additional expensive.
Personally, I think I would also order the iMac with the minimal possible amount of RAM (8 GB) from Apple and then also buy OWC's (or another good-quality make's) 64 GB iMac RAM kit to install in it:
https://eshop.macsales.com/shop/memory/iMac/Retina-5K2015/DDR3L . That too would be only a small difference in cost overall, compared to buying it with just 32 GB from Apple.
Best regards, Martin.
Hauptwerk software designer/developer, Milan Digital Audio.