There's an add-on for Audacity to use ASIO. I think the problem is that add-on won't release the driver when Reaper is switched back to the fore-ground and Audacity is closed. I think I ran into the same trouble with Audacity when I tried it out. These days, I use Adobe Audition 1.5 exclusively as an external editor. I keep Audition set to use my EMU1820M's Wave driver (WDM) and Reaper uses the ASIO. No conflicts, no problems. D