Noob here. I hesitate to actually edit this page, but I've been trying to get a Langstone system working with Pluto, Pi4, Raspbian. I was having trouble with error msgs or if no msg, there was still no audio. I tried many edits with no luck, performing a "shutdown -r now" after each change. It turns out that a COLD BOOT was needed.
Both "hw:CARD=Set,DEV=0" works for a simple CMedia fob, as does "hw:CARD=H540,DEV=0" for a Logitek USB headset. In both cases, COLD BOOT was required. This MAY be unique to RPi issue. However, a footnote might add value for other RPi users.
Also, on this page, under the Linux section, it has a note that the double quotes "hw:......" are NOT to be used. It appears they are in fact necessary or there is a Syntax error.
On my rPi 3B+ with Raspbian OS, I did not have the problems described. Also, as long as there are no spaces in the device name, the quotes should not be needed. I don't use them. They probably don't hurt in any event. As far as the shutdown, make sure you are terminating by clicking the X in the corner of the screen which comes up when you run. Clicking the stop icon in GRC does not always terminate everything.
- Barry Duggan