Output level reduced by 30dB

[Privatier]

I had used REW for several months on my desktop computer with Linux Mint 20 without problems, until a few days ago the output signal has always been 30dB smaller than the level set in the generator or measurement setup. My voltmeter shows the much smaller signal, and REW displays the corresponding much smaller input voltage. I have done a "delete preferences and shutdown", uninstalled and re-installed REW, no change. Other sound applications work just fine, like playing a sinewave signal produced by sox or saved from the REW generator. Running REW in a different user account on the same computer works just fine. Utilities like amixer or pavucontrol do not show attenuation anywhere. Any hints for other settings and tests are very much appreciated.

 

[Privatier]

By chance I found the answer to my problem: the "Sound" app has a tab "Applications". While REW sends a waveform to the output, then in this tab "ALSA plug-in [java]: ...%" is displayed. When I discovered this, the gain was set to 39% instead of 100%.
I still do not know where this particular setting is stored; it's somewhere in the home directory, and survives when restarting the computer. The utility "alsa-info.sh" does not report the plug-in while it is active.