'regime-change' @ Leap-15.5

My previous 15.x and 15.y upgarded twice or more to 15.5 finally got to the point where it would recognize only that one of my two soundcards that wasn't plugged-in at the time. DON'T ask me hoe it did that!!! So I did a fresh install and am tweaking it. The card in use is a CMI8788 XONAR Essence STX-II. It gets recognised but there's this issue in the pulse Volume window: Input-Devices, port "whatever" selected, the slider remains DEAD. Since I use my compuker mostly for guitar sessions this is a no-go, my playing makes dogs howl but it risks getting better if I can't hear it