IOhannes,
I'm aware of the sequence of launching apps from OS X - I use Pd there with Jack and it works flawlessly. My mac is away for service, so I seriously needed to get started with Linux on another computer.
This time I wanted to be very sure so I checked carefully - the moment Jack is selected as audio device in Pd it appears in Jack's connection panel. So I made sure that both in and out of Pd are connected to the 'system' and after that clicked in Pd on 'apply'. And it is working now :-) the sky is full of violins
I checked on using ALSA directly from Pd but it doesn't work - no feedback on the canvas and no output. This is like my audio hardware under OS X which also doesn't work directly from Pd. So I didn't really expect it.
Thanks for your advice and time, very much appreciated.
Jurgen
Pd-vanilla at least will not startup a jackd automatically, so jackd has to be running before you start to Pd (or switch to jack).
also note that switching audio-apis might work less than starting Pd with the correct API from the beginning.
e.g. use something like "pd -jack -channels 8"
mfgasdr
IOhannes