ALSA vs JACK

In my experience, alsa is adequate for multi i/o sound devices, and is generally what i use for all my programs.  its hassle free and no frills.  Jack tends to be a mystery when its not working and tends to boil down to rebooting a machine and setting it all up again.  mysterious things happen with jack but it does offer a much deeper flexibility than alsa.  some programs require jack such as renoise.  so its good to know how to use it.  youtube has a lot of videos from the entire emergence of jack onwards and is hard to tell what is relevant and what is outdated info.  i find that if i immersed myself in the videos thing would gel and its the only reason i know what i do and can get as far as jack has allowed me lol!  im no expert, but i can answer questions to the best of my understanding.

qjackctl is a utility i have installed that allows you to make changes and view connection diagrams etc.  start menu > run > qjackctl