Dark Brown CMYK

[digitalphaser]

...Yes it's all the darker colours that cause the real problems, the maroons and dark greens can look really muddy as well as you found out the darker browns...

Aha, that is, the problem is present. It has relieved me.

As for the monitor calibration. I have only bad experience with Spyder4Pro. It is good to know that your computer is calibrated. But in practice, the result is rather disappointed as well. Maybe for RGB photographer is good, but not for prepress PDF Workflow. So, a matter of taste. Of course Acro Pro is always there.

Yes, Illustrator is not much better. CorelDraw is, at least earlier versions, very bad.

...You have to get yourself a reference and if you don't want to spend £200 on a pantone book...

For CMYK I use DuMont Color Atlas with CMYK values.

In any case, thanks for the tip.