There are ways to avoid the memory fault (reduce the number of periods to 512 is one, i.e. -p 512), but I've yet to encounter a solution to running Jackd 2.0 successfully for general use as it requires the alsa driver to have memory mapping support, which it doesn't seem to have.
I have seen a thread that suggests running an older version of Jack 1.9.8? with the "dummy" driver and using alsa_in, alsa_out to communicate with it via your applications. However none of this has been stable when I have tried. Other people have had more luck though!
I'm of the opinion that we need to wait a bit for the sound drivers to mature. I wish I could help as there is a growing clamour (I want mic-pass-through for my Karaoke app!, etc..). I'm the same.. for some reason all of my off-the-wall projects seem to involve audio or USB. I think my students quite wrongly summed it up today (they are getting fed-up of my Pi stories).. "If you keep on at your Pi, you'll forget how to program a proper computer!". Sigh.
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