Audio: Way to disable HDMI or set USB as default?

[SerbJ]

With my Pi 4B and Moode 9.3, if I power up without the USB DDC plugged in, it will default to HDMI on 0 and 1.   Wait a few minutes and plug in the USB DDC, and shows up a 3: SMSL USB Audio.  The 0: HDMI is still the default, and have to change it in the Audio config.  If you just try to play, a warning pops up saying no device detected on HDMI, and will not play or see the USB Audio at that time and switch.  I assume that if the HDMI was connected to a display, it would just go on its merry way.

It didn't work that way in 8.x.x, and thanks for the explaination why.  

A possible work-around, H/W solution for the OP, is using a DDC and connecting to the DAC via SPDIF (coax or optical).  The SMSL PO100, $40, only draws 300mA from the USB bus.  Just a suggestion.

What do you have set for "Device ready wait"?

The default, which I think you said that was 1 minute.   

Please note that I do not have an issue.  My Pi is off when not in use.  The DDC is left plugged in to USB 2.0 port.  When Pi is powered on, so is the DDC, and the audio config shows that it connected to the correct device.  With my old DDC, which had an external PS, if I forgot to power it on before the Pi, this would be an issue.  Which I am assuming setting the "Device Ready Wait" to something longer, would help.  

I ran into this a few times when I was just configuring the Pi without the DDC connected.  For the test case above, I waiting about 5 minutes before plugging the DDC into the USB port.   I then waited about another 5 minutes to see if it would switch from HDMI to the USB.  

The behavior was different from 8.x.x, but now that I know, not a problem for my set-up.  

For the OP, this should work with the Pi and DDC always on.  If the Pi reboots, the DDC is still on.

[nikolas]

Yes if you reboot the pi while the USB DAC is off the startup process will fall back to HDMI after the "Device ready wait" has expired. The default wait period is 1 min but can be set to 2 or 3 mins.

In your post 33 describing the steps you stated "1. RPI always on forever" which is the scenario I tested.
https://moodeaudio.org/forum/showthread....1#pid63101

I think there is another scenario where at some time after the fallback to HDMI has occurred, the USB Audio device is turned on or plugged back in and rather than having to open Audio Config and manually set the Output device it is  automatically set when the USB Audio device is detected. Its could be doable but I'm not sure how much work is involved.

The "other scenario" is also the issue that remains for me, though I agree that its not very important. I wondered whether it could be fixed by making Moode save the last device the user chose somewhere. Then as long as the active device does not match the last chosen device (because the fallback to HDMI occurred), any time a new audio device shows up, Moode would just need to briefly check whether its the device the user chose and if so, switch output. As with anything, that's probably easier said than done. And others may be happy with the fallback and would prefer not to revert. And its just minor details, appreciate all your attention to sorting it out!