I now have twinkle working again with ALSA. A quick-and-dirty patch is to change "plughw:0,0" to "default:" in audio_device.cpp:-
$ diff -u audio_device.cpp audio_device.cpp_original --- audio_device.cpp 2021-01-07 22:35:15.862448988 +0000 +++ audio_device.cpp_original 2021-01-07 21:57:51.119873744 +0000 @@ -887,12 +887,9 @@ if ((err = snd_ctl_pcm_info(handle, pcminfo)) < 0) continue; t_audio_device dev; - /*dev.device = string("plughw:") + int2str(card) + - */ - dev.device = string("default:"); - /* + int2str(card) + + //dev.device = string("plughw:") + int2str(card) + + dev.device = string("default:") + int2str(card) + string(",") + int2str(device); - */ dev.name = string(card_name) + " ("; dev.name += snd_pcm_info_get_name(pcminfo); dev.name += ")"; The previous audio device is also stored in ~/.twinkle/twinkle.sys, so it is very likely that will need editing as well. No doubt that can be done from the twinkle gui as well, but I have not explored that as well.