Is there a way to widen the gamut of a CMYK print so that the darks stay dark and the lights stay light? I suspect it has something to do with color space being exported, but I don't know how to approach making changes to it. Also any other hints of workflow adjustments to help guarantee accurate colours?
I recently had some proofs done with the same Indesign generated PDF (with a few CMYK AI files and a number of photos) at two different printers on similar matte stock. I did everything I thought I should to make sure the colours are right... saving the AI and INDD files in CMYK and not doing any explicit conversion to the placed RGB photos until exporting to PDF.
One of the prints I found the colours were generally darker than what I was looking at on my screen and some of the darker areas lost some details. The other print had the opposite problem... the colours were a bit brighter, and lost some detail in the lighter tones. Generally I've noticed that things I get printed are generally a bit darker than I see on my screen at a few different places.