JACK Audio Connection Kit
Multiprocessor implementation (soon: JACK2)
Here's a mp version of JACK which will also be used as base for JACK2. However, I couldn't figure out how to use it - if you do, please edit the wiki.
AUR package: jack-audio-connection-kit-mp
Alternatively, there is the normal version from the extra repository, install it with:
pacman -S jack-audio-connection-kit