How to apply Colour Profile to new printer

I have installed a Brother MFC 9330CDW to my home network, with all sorts of protocols enabled. The iMac sees airprint and CUPS. Test pages are fine, but when I print a full colour image (not trying photoshop or anything fancy), the quality is appalling - anything darker than 50% grey turns out black.

On the same network I have printed from windows 7, 8.1 and two win 10 machines. The windows 10 machines were initially as bad as the iMac, but I managed to fix them by forcing them to use one of the default icc profiles - sRGB or Agfa SWOP. Both gave quite similar results (I don't expect subtlety from a laser printer).

When I check the help for applying a colour profile in OSX, it tells me that I do it in the print page dialogue. But I can find no such thing when I print from the default preview app.

If I open with ColorSync Utility, and assign the default CMYK profile to the output then it still makes no difference to the print quality, and it does not remember my setting either.

Any pointers as to where I am supposed to fix this?

Thanks