Caution: naivety ahead. I'm seeing similar behaviour, but I'm not sure it's identical. I don't have "load-module module-alsa-sink" uncommented in /etc/pulse/default.pa. I've also rebuild pulseaudio with the patches but my problem persists.
With no USB audio devices connected, pulseaudio works fine. Connecting either my (USB) Yamaha AG06 mixer or my Behringer UMC204HD cause pulseaudio to segfault. I built a debug version of pulseaudio. Here's the backtrace when it segfaults: (gdb) bt #0 0x00007ffff29bd0d7 in snd_async_del_handler () at /lib/x86_64-linux-gnu/libasound.so.2 #1 0x00007ffff29d7549 in snd_pcm_close () at /lib/x86_64-linux-gnu/libasound.so.2 #2 0x00007ffff29ea559 in () at /lib/x86_64-linux-gnu/libasound.so.2 #3 0x00007ffff29d756d in snd_pcm_close () at /lib/x86_64-linux-gnu/libasound.so.2 #4 0x00007ffff2adeeae in _snd_pcm_a52_open () at /lib/x86_64-linux-gnu/alsa-lib/libasound_module_pcm_a52.so #5 0x00007ffff29d3c45 in () at /lib/x86_64-linux-gnu/libasound.so.2 #6 0x00007ffff29d42a7 in () at /lib/x86_64-linux-gnu/libasound.so.2 #7 0x00007ffff29d71e8 in snd_pcm_open () at /lib/x86_64-linux-gnu/libasound.so.2 #8 0x00007ffff292f1b3 in pa_alsa_open_by_device_string (device=0x555555971270 "a52:3", dev=0x0, ss=0x7fffffffdb74, map=0x7fffffffdb80, mode=0, period_size=0x7fffffffdb58, buffer_size=0x7fffffffdb60, tsched_size=0, use_mmap=0x0, use_tsched=0x0, require_exact_channel_number=true) at modules/alsa/alsa-util.c:702 The code at line 702: if ((err = snd_pcm_open(&pcm_handle, d, mode, SND_PCM_NONBLOCK| SND_PCM_NO_AUTO_RESAMPLE| SND_PCM_NO_AUTO_CHANNELS| (reformat ? 0 : SND_PCM_NO_AUTO_FORMAT))) < 0) { Is this likely to be the same bug? If so, should the patch have fixed it? What more information can I provide to help?