Keyboards on flat table?

I am wondering if it is ok to place the KB (Korg Pa900 and Yamaha s970) on a flat surface vs a stand because I don't know if there are "breathing" vents on the bottom of them.

It really shouldn't matter because there are always rubber feet on the bottom of keyboards that keep space between the bottom of the keyboard and flat surfaces it sits on that allows ventilation.

ok, thanks!