On 06/06/18 14:12, Mac wrote:


....

Apparently not. I tried "jack_control dps device surround71:PCH,0" and still got playback_1,_2. (There are also surround21, 41, etc. none of those changed anything either.)
As for hdajackretask, when I tried to "Apply now" I got a device busy message. I didn't try "Install boot override".
 
In my case the real answer is I don't know. I tend to disable any internal audio device to clear up one more thing that may interfere with "real audio".


I use qjackctl, so I'm not that familiar with the command line interface.
In the Qjackctl settings panel, under advanced, it shows the 'system' output device,
and also a field for number of channels. I had an 8-channel DAC connected a while back
and setting channels=8 and restarting produced 8 system outputs. So it is possible.

Looking at web pages for jack_control, I'd suggest trying:

    jack_control dps device surround71LPCH,0
    jack_control dps channels 7

might be the answer?
Bill
-- 
+----------------------------------------+
| Bill Purvis                            |
| email: bill@billp.org                  |
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