I have used the onboard sound (Realtek ALC892 7.1) since Debian was installed. But today I put a new soundcard (LogiLink PC0043) into a PCI slot and disabled the onboard sound. After booting there is sound from the new soundcard, but no Mic sound. I guess maybe the old drivers are still in use. What to do?

lspci -nn | grep Audio
02:00.1 Audio device [0403]: NVIDIA Corporation High Definition Audio Controller [10de:0be3] (rev a1)
05:00.0 Multimedia audio controller [0401]: C-Media Electronics Inc CMI8738/CMI8768 PCI Audio [13f6:0111] (rev 10)

And:

alsactl init
alsactl: sysfs_init:48: sysfs path '/sys' is invalid

Found hardware: "HDA-Intel" "Nvidia GPU 0b HDMI/DP" "HDA:10de000b,10de0101,00100200" "0x1462" "0x2400"
Hardware is initialized using a generic method

If sound is coming from the new soundcard, it is being recognized. Your next step is to fiddle with the audio settings with something like Alsa mixer. It may be as simple as clicking on the Mic mute toggle.

But my experience is that some sound cards have weird linux driver issues that no one has fixed properly. In particular, I have a Motion Computing LE1600 which has weird but functional support. For some reason, the headphone output goes to the microphone jack rather than the headphone jack. I don't have a microphone to test with, but I expect that functionality is probably just missing. I don't think any linux driver coders have access to a Motion Computing LE1600 so that's why no one has fixed it properly.

That said, if your sound card has a common enough chipset and doesn't have a bizarre configuration, it should hopefully work fine out-of-box. But like I said, you may have to fiddle with the alsa mixer settings.

Installing and running pavucontrol is often the quickest option.

1 members found this post helpful.

Cant believe it, the Mic was muted in the mixer (pavucontrol). Now it all works. I increased the microphone volume both at recording and input. =

I can - been there, seen that. Sound can be a mystery, but it's actually easier than it used to be! Glad all's well.