Why is the system recording (both WASAPI and Stereo Mix) syncing with volume?

I’m using MME/DirectSound’s Stereo Mix and WASAPI’s loopback to record audio. However, when I use either of them, the recording depends on the system volume, and I need to keep a low volume to not blast my ears, but the signal is too quiet. My headphones and laptop don’t have an external knob to control the output volume that doesn’t affect system volume.

I’ve seen other people recording WASAPI audio with a very good volume while having a low system volume value. How can that be possible?

With loopback or stereo mix you are recording the output from your soundcard.

Regular plug-in computer speakers usually have a volume control knob. Or if monitoring isn’t critical plug-in headphones and you don’t have to put them on your ears.

Sure, I could take them off while recording, but I’ve been told there’s a chance that super loud volumes could damage headphone speakers.

It’s highly unlikely that your computer’s headphone jack can put-out enough power to damage headphones. You are more likely to damage your ears than the headphones (if wearing them).

With external speakers, you’ll have a volume knob. And depending on what you buy you can get much better sound than the speakers built-into a laptop.

You could also plug-into your stereo or TV if you have the right cables.

You can also get an inline headphone attenuator/volume control.

Or if you don’t need to monitor at all, you can plug-in a headphone extension cable with no headphones to fool the computer into turning-off the speakers.