I have been trying everything I can find, but I keep getting errors that Jackd can't initialize through ALSA. I even found a few other people who had the same troubles in the mailing list archive for this forum, but their questions were unanswered. I'm not sure if there is some way to connect Jackd directly to the AudioInjector - but trying to connect it via ALSA does seem to create some problems.

When I run "aplay -l", I can see AudioInjector is listed as Card 2:
card 2: audioinjectoroc [audioinjector-octo-soundcard], device 0: AudioInject-HIFI cs42448-0 [AudioInject-HIFI cs42448-0]
  Subdevices: 1/1
  Subdevice #0: subdevice #0

My thinking is that what I'm supposed to do is run this line:

jackd -d alsa -r 44100 -P hw:2

But this causes the Pi to freeze.  I think there's a lack of information on how to do this without a GUI, specifically.  Also, it is unclear to me how I might modify the .asoundrc file, since I set it up according to the Audio-Injector instructions.

If anyone has any specific suggestions, I would definitely appreciate it!