Hello there.
We've installed Polycom Group 500 with a Skype for Business license in a directory here in Santiago Chile, with a combination of external and native mics. The client's complain is that at the other end of the call the audio (our microphone array) is too low, and that they're having a hard time trying to understand whatever is mentioned on the call.
Group 500 device has the 6.1.7 software upgrade, has transmission gain of 18 (maximum), 3,5mm input gain of 7 for external mics array (if increased to 8,9 or 10, it only distorts the signal, but volume doesn't go up). Audio from the mics array mixer is very healthy. Plus we are using the default Group 500 Polycom microphone.
Attached are some screenshots of the Polycom web server administrator.
Will be waiting for your answer.