Thank guys, for providing some ideas.
Hitman, do I understand you to be suggesting that I run one instance of ST as Standalone_JACK, and the other instance as Standalone_ALSA.
While I find that two instances of ST_JACK can't run without causing all kinds of exciting glitching, running one JACK and one ALSA does not upset the JACK instance . . . so far, so good.
What I can't figure out is how to get the output of the capture sound card into the input of the ALSA ST. It is wired via JACK into the JACK ST, and that works fine. I ran the suggested 'sudo modprobe snd-aloop'. Here is the output of arecord -l:
Code:
jack@jack-20428:~$ arecord -l
**** List of CAPTURE Hardware Devices ****
card 1: PCH [HDA Intel PCH], device 0: CX20756 Analog [CX20756 Analog]
Subdevices: 1/1
Subdevice #0: subdevice #0
card 2: Device [USB Audio Device], device 0: USB Audio [USB Audio]
Subdevices: 1/1
Subdevice #0: subdevice #0
card 3: CODEC [USB Audio CODEC], device 0: USB Audio [USB Audio]
Subdevices: 0/1
Subdevice #0: subdevice #0
card 4: Loopback [Loopback], device 0: Loopback PCM [Loopback PCM]
Subdevices: 7/8
Subdevice #0: subdevice #0
Subdevice #1: subdevice #1
Subdevice #2: subdevice #2
Subdevice #3: subdevice #3
Subdevice #4: subdevice #4
Subdevice #5: subdevice #5
Subdevice #6: subdevice #6
Subdevice #7: subdevice #7
card 4: Loopback [Loopback], device 1: Loopback PCM [Loopback PCM]
Subdevices: 8/8
Subdevice #0: subdevice #0
Subdevice #1: subdevice #1
Subdevice #2: subdevice #2
Subdevice #3: subdevice #3
Subdevice #4: subdevice #4
Subdevice #5: subdevice #5
Subdevice #6: subdevice #6
Subdevice #7: subdevice #7
The target input device is "card 2: Device [USB Audio Device]"
The running ALSA ST does not show that as an input option. Here are my choices:
https://imgur.com/a/EENrxuJ
None of the options pick up the audio from the card. Meanwhile, over in JACK land, that instance of ST is getting audio from the card. So the card is working.