[tde-users] kmix - audacity - hiss & feedback when recording

Just wondering if anybody else here has encountered this problem, and what to do about it. When I play an instrument through kmix, I must enable loopback mixing, but this creates a hiss in the speakers, which in turn tends to create feedback -- in particular, when I plug in a hollow-body electric guitar. This has only been a problem since I upgraded from Devuan Jessie. I used to play through my computer speakers all the time, using them like a guitar amplifier. (There is another device, a headphone amplifier, which I use as a kind of pre-amp.) But otherwise, nothing in my setup has changed, except that I have upgraded to Devuan Beowulf. I would like to get rid of that hiss, and I don't remember having to enable loopback mixing before. I have only recorded a little since upgrading (using audacity), but it doesn't seem to affect recording quality too much, because I plug headphones into my computer speakers, which eliminates both hiss & feedback problems. Sorry for the detailed presentation; feel free to snip. The main problem is kmix-trinity, and whether anything has changed between Devuan Jessie and Beowulf, namely, loopback mixing. Or have I somehow misconfigured it? Bill