Photo prints invariably too dark

I am using LrC on an iMac 27 inch, color corrected with xRite i1Display Studio.  Before printing on my Canon printer or sending work out to a photo lab, I have been pre-checking the images  in the Lightroom Develop Module by Soft Proofing with a profile appropriate to the photo paper.  The results I acheive on paper are true as far as color, but are always too dark for my taste.  Maybe by as much as a full stop from what I am seeing on the screen.  It is not an issue limited to my printer, or partiular paper, and it is true with B&W prints, too.  I am guessing its an issue with my White Point being set too high on my monitor.  But before monkeying around with it, I thought I would ask the community for ideas how to get what I am seeing on the screen closer to what comes out on paper.  

Also, on the LrC Print Module, there is a slider under Print Adjustment called "Brightness."  I have no idea what it does and it doesn't seem to change what I see on the screen.  Is that the place to fix this?

Thanks in advance for sharing your wisdom and experience.