When I check the box next to sample rate in project settings it causes REAPER to stop responding...is it necessary to check that box when setting the project sample rate? It seems to do nothing, at the rate stays set to whatever I change it to...
I thought it was to override the sample rate setting in Preferences/Audio/Device. Allowing you to load a saved project that runs at a different sample rate than you usually work at and not have to make the change in the preferences page.
Box ticked = connected audio interface(s) are switched to that sample rate
Box not ticked and project sample rate set differently than connected audio interface(s) = Reaper allows you to use the hardware running at a different sample rate and sample rate converts the project audio on the fly.
Normal operation with matching project and hardware sample rate is the normal way to operate. Any audio items at a different sample rate are sample rate converted on the fly to the project/hardware sample rate.
Then there's the enable 'snap to project sample rate' feature in the grid dialog. Which is where I always found this control.