[LAU] MOTU AVB series sample rate issue, JACK, and PulseAudio

tl;dr: Has anyone figured out a convenient, reliable way to setup MOTU AVB series interfaces? Hi, I recently got a MOTU Ultralite AVB to replace my RME Babyface Pro. RME advertise the Babyface Pro as working with Linux without proprietary drivers and because all essential functions can be controlled directly from the device, but that is not true. It is not possible to directly monitor a mono input on both sides of a stereo output. It is possible to hack around this with Y splitter cables on the inputs, but that's clunky and halves the number of available inputs. I contacted RME about this and pointed out an unused button on the device that could be used for toggling mono/stereo direct monitoring with a firmware update, but they did not care. It seems they only care about their own use cases, namely iOS. Apparently they can't be bothered to make minor changes for Linux users but are happy to misleadingly advertise Linux compatibility. So I got a MOTU Ultralite AVB to replace the RME Babyface Pro. The sound quality is on par with the Babyface Pro but the Ultralite AVB has more I/O and features for a lower cost (although if recording guitar is important for you, IMO the Babyface Pro's instrument inputs sound clearer than the Ultralite AVB -- but keep in mind the direct monitoring issue). The Babyface Pro has some quirks when using it with GNU/Linux (which I think are caused by the 2 channel mode it has for iOS), but the Ultralite AVB has different quirks. As discussed on this list previously, there are some oddities trying to set the Ultralite AVB's sample rate. This seems to cause some issues with PulseAudio. If I start PulseAudio with the Ultralite AVB plugged in, it works briefly but randomly drops out. When I plug in the Ultralite AVB after PulseAudio is started, it does not appear as an output for PulseAudio and I see this in PulseAudio's output: E: [pulseaudio] module-alsa-card.c: Failed to find a working profile. E: [pulseaudio] module.c: Failed to load module "module-alsa-card" (argument: "device_id="1" name="usb-MOTU_UltraLite_AVB_0001f2fffe005a12-00" card_name="alsa_card.usb-MOTU_UltraLite_AVB_0001f2fffe005a12-00" namereg_fail=false tsched=yes fixed_latency_range=no ignore_dB=no deferred_volume=yes use_ucm=yes card_properties="module-udev-detect.discovered=1""): initialization failed. Occasionally I also see this in the output when I start PulseAudio with it plugged in already. This seems to appear randomly and is not correlated with PulseAudio output dropping out: E: [alsa-sink-USB Audio] alsa-sink.c: ALSA woke us up to write new data to the device, but there was actually nothing to write. E: [alsa-sink-USB Audio] alsa-sink.c: Most likely this is a bug in the ALSA driver 'snd_usb_audio'. Please report this issue to the ALSA developers. E: [alsa-sink-USB Audio] alsa-sink.c: We were woken up with POLLOUT set -- however a subsequent snd_pcm_avail() returned 0 or another value < min_avail. Sometimes it looks like PulseAudio tries to set the Ultralite AVB to a different sample rate. I sometimes notice the LCD display on the Ultralite AVB showing 192 kHz when PulseAudio tries to use it. I tried setting this in /etc/pulse/daemon.conf: default-sample-rate = 44100 but it made no difference. So I have tried using JACK regularly with the PulseAudio to JACK bridge. Unfortunately this has some quirks too. JACK won't start unless I wait several seconds after plugging in the Ultralite AVB. If the Ultralite AVB is plugged in when I boot up and log into KDE, QJackCtl autostarting JACK doesn't work. I think this is because PulseAudio tries to grab the device before JACK starts. I have to wait a few seconds and manually start JACK. If the Ultralite AVB's firmware is set to a different sample rate than JACK is configured for, JACK won't start. Has anyone contacted MOTU about the sample rate switching issue? Ideally they could make it just work when the computer tells the audio interface to switch sample rates. Also, has anyone contacted them about possibly changing the firmware so the web interface is available over USB on Linux? I think if they used the RNDIS Ethernet-over-USB protocol that Android uses for tethering it could be plug-and-play with Linux. Or has anyone started working on a custom driver to make this work? In the meantime I got a cheap little GL-MT300A router ( http://www.gl-inet.com/mt300a/ ) to use the web control interface away from my home network. It's neat. :)