Reaper latency MacBook Pro max direct usb connection

Reduce the buffer size in the Audio device settings in Reaper (they call it block size with some audio engines). You currently have it set to 512 samples, which is pretty conservative. Depending on the performance of your computer, you can likely lower it quite a bit. I typically run mine in Windows at 32 samples. Smaller buffer means less latency, but comes at the cost of CPU load. If you start getting dropouts or artifacts, turn it back up a bit until those go away.

Like GlennO said, when you monitor direct (software monitoring is turned off in Reaper) you have no additional latency. Latency only really matters when you are trying to monitor the DAW output in real time like when using software instruments or monitoring plugins on the input in real time.