[Glennbo]

I'm running Xubuntu and have Pulse Audio set to use my motherboard audio so there's no conflict for REAPER to use my 8 input USB audio hardware. In REAPER I only had to choose ALSA and then select my UMC1820 from the list.

I did do the tweaks elevating my user profile for unlimited memory and RT priority privileges, plus set the RT priority of my USB sound device to 98% and installed the linux-lowlatency kernel. I run my sound device at 64 samples latency and 4 periods with no artifacts in the audio or sluggishness in response.