This is essentially the same as the Ask Ubuntu question How to use JACK and Pulseaudio/ALSA at the same time on the same audio device?.
However, the answers to that question are all incomplete in at least one important respect. They don't specify how to set things up so that Pulseaudio will run on top on Jackd on bootup. They also seem to assume that QjackCtl (a GUI) is used for JACK configuration. This is not appealing.
I was recently able to reconfigure PulseAudio so that it ran on top of JACK. This was very simple. I followed the instructions in this Fedora tutorial.
I just edited the file
/etc/pulse/default.pa to add the following lines after the line
load-module module-jack-sink load-module module-jack-source
Then I killed PA, as recommended by the Fedora tutorial. PA then started again, but this time on top of JACK.
However, when I rebooted recently, neither JACK or PA started.
So I'd like a more complete solution which works on reboot. I also want a solution that is solely based on modifying config files, not using a GUI. An explanation for how and why the proposed configuration works would also be much appreciated.
I'm using Debian Jessie (8.3). However, I'd like answers that apply as broadly as possible, for maximum usefulness. Clean approaches which don't use the approach of the Fedora tutorial are also fine, of course.
It's also worth noting that the JACKD project itself has configuration recommendations, in Running PulseAudio on top of JACK and How use PulseAudio and JACK?. But I'm not sure what it is telling me to do.