Math question: Where is zero gain on the Windows 10 level slider?


Hello all. I'm using a Benchmark ADC1 USB to rip vinyl. It uses the generic Windows 10 "USB microphone" driver. I want to set this to zero gain per advice from Benchmark. Unfortunately the levels setting in Windows 10 is calibrated in percent, not dB.

It seems like we should be able to figure out the exact setting for 0dB gain in the Windows 10 sound control panel. I discovered that the "0" level in the Windows sound control panel for the "USB microphone" corresponds to -96dB and the "100" level corresponds to +30dB. However, being a sound level setting, I'm guessing it's logarithmic and not linear. (If it were linear, 0dB would be 76%, which seems too high.)

Does anybody know the math well enough to derive the 0dB setting? I'd really like Windows to just leave the signal completely alone, and use the Benchmark to set the level.
gweadock
Everything I know about math I learned from the professor here. 
https://www.youtube.com/watch?v=MS2aEfbEi7s
I would set the Windows level to 100% so that you get the full bandwidth of digital data.  The actual "gain" should be configured on the Benchmark ADC itself.  Your goal is to get a hot enough signal on the Benchmark input to allow the ADC chip to produce enough "bit level" bandwidth to capture a good enough resolution.  Use the LEDs on the front of the Benchmark to adjust your input recording level.
But 100% on the slider is a 30dB boost. Benchmark says the Windows driver ideally should be at zero gain.
So, the question is, if 0% is -96dB, and 100% is +30dB, where is 0dB on this slider?
To close out the topic, I was advised that the best approach is to bypass the Windows volume control altogether by using ASIO4ALL, which passes the signal with zero gain. That method seems to be working well. Hope this helps anyone who might have this question in the future.
Hi gweadock,

Might be a late response, but I was looking for this exact answer and found your reply.

But there is another simple option which I stumbled on.

If you right click on the microphone level slider in windows sound control panel for your USB microphone, you will get two options:

percentage or decibels

Select decibels and it'll be exactly what you want.

My zoom H1 USB microphone was +0.1dB at 54 percent level.

I found different devices can have a different 0dB point so check yours.

Good luck.
Thank you chocman, you are absolutely right! I never knew that option existed.
The award for "most non-obvious setting in Windows" goes to the microphone level slider.
I also got +0.1dB at 54 percent with the Benchmark ADC. I may still keep using ASIO4ALL though because it seems to bypass the Windows volume control entirely.
Many thanks for the tip!
No problems! I wish Windows would stop making it harder to find these things, why not have a tick box for dB?....
100% agree. Terrible user-interface design.