Clics/desync/echo while recording

After much trial and error I've finally managed to get RSASIO/Reaper/OBS to cooperate and record.

I've a much smaller, but still annoying, problem now: there's clics/desync/echo on the recorded audio tracks. I've tried changing the sample size from 128 to 48 but the issue persists. I've not touched the sample rate though. Is there anything I'm missing?

EDIT: For anyone having the same problem, I've managed to fix it.

Against what most advised, increasing the buffer size did it for me. Setting it at 192 fixed the crackling. Also, disabling the microphones in OBS! That's very important. I noticed my voice wound up in one of the recordings when I sung a chorus and that led me to notice OBS had more than one input going.