The Avee512 XLR-5 aircraft adapter now comes with a built-in headset volume control and a microphone gain adjustment possibility.
The reason for adding the headset volume control on the Avee512 XLR-5 adapter is that some headsets (like all Sonys and the Bose QC25 and QC35)  do not have a built-in adjustment feature.

On larger aircraft like Boeing and Airbus, the pilot cannot adjust the volume level on callouts, so they can be annoyingly high without an adjustment possibility. This issue is now solved.
On small aircraft, the radio volume level is often common for the left and right seats, and missing the adjustment possibility can be annoying.

It is a fact that headsets from different suppliers ( David Clark, Lightspeed, and Bose A20/30) do not have the same earphone output volume so an adjustment possibility comes in handy.

We recommend that pilots using the Avee with a headset that has a built-in adjustment feature crank up the volume to max on the headset and make adjustments from the Avee aircraft adapter instead.
This is to avoid as much of the annoying tin can feature on your own voice (which some pilots experience) when talking.

The mic gain adjustment that can be operated with your thumb-nail or a credit card, must be handled with great care: setting the output volume t0o high will make the microphone pick up more noise from the cockpit.
The default setting (arrow point right up) works well for 99.87% of the users.