I suppose this is properly a KDE issue and maybe a bug, but I thought I would start here and see if there is any insight into the question:
I am one of a dwindling population of linux users who does not use Pulseaudio. I have an “.asoundrc” file which in defines a number of sound devices which KMix in earlier KDE versions would display in its Audio Setup page. I have found that the KMix version which now comes with KDE5 does not list any of these devices, but instead lists only “Default”. I have dealt with this problem by downgrading KMix to an earlier version (4.14.3 to be precise) which will then list all of my defined alsa devices and let me assign them to the various categories. Although this works I imagine that as time goes on and KDE 4 becomes a distant memory, this will become problematic. Am I missing some tweak to KMix 15.x.x that will allow it to interact more meaningfully with bare-bones alsa? Is this a “feature”, rather than a bug? Is it a sign that we are gradually being shoe-horned into using pulse?