The only thing I could contribute to the conversation so far would be to NEVER use PulseAudio, and commit to using JACK for all your audio I/o needs, with regards to setting up Linux (UbuntuStudio) as a high-performance DAW.

This is really the great thing about Linux: we've got tons of options when it comes to audio I/o routing .. but its a liability too. My advice: commit to setting up Jack and learning it - definitely the best thing about Linux Audio.