REW + UMIK-2: Why does LZpeak never exceed 111.6 dB?

[Dannymultimedia]

Using REW with a UMIK-2. LZpeak never exceeds 111.6 dB regardless of playback level. Windows mic gain tested at 100%, 50% and 5%. REW restarted and Min/Max reset multiple times. SPL clearly increases, but LZpeak remains fixed at 111.6 dB. Is there a measurement limit, calibration issue or configuration setting that could cause this.

I have watched multiple YouTube videos, searched through forum discussions, and spent a lot of time troubleshooting, but I am still unable to figure out what is causing the problem.

Windows 11.
miniDSP UMIK-2 microphone.
The correct calibration file has been downloaded and loaded into REW.

 

[John Mulcahy]

There's a small app you can get from miniDSP to adjust the mic's internal gain. The windows gain just scales the data, it doesn't alter the analog clipping threshold.