Many thanks to SWLing Post reader, Paul, who writes:

While putzing around with my new Tecsun PL-880 that I got while browsing at Universal Radio’s store in Columbus OH, I found what appears to be an adjustable noise reduction function.

Firmware level: 8820
Mfg date: probably August 2016 (201608 from the serial number inside the tilt stand)

Here are the steps to check it out;

When in a shortwave band, press “4” until either “ON” or “OFF” appears in the display.
If it displays “OFF”, press 4 briefly to clear, then long press again until “ON” appears.

Then, long press “9” until a two digit number appears.

Use either tuning knob to increase or decrease the number.

The number appears to correspond with the DbM threshold of the received signal.

Perhaps someone can play with the feature and elaborate on its function.

Hope this is useful, let me know.

Thank you for sharing, Paul!  I do wonder if this adjustment could affect the DNR setting (check out this previous post as well).

Post readers: Has anyone else been able to replicate and test this hidden feature? Please comment!