Yes, ReSound has in situ audiometry, too, by which you can effectively measure the softest sound that you can hear at each test frequency and also test whether each HA is capable of producing an “Uncomfortably Loud” sound - showing the output is still capable of approaching the MPO for that frequency. However, AFAIK, the in situ audiometry does not allow you to evaluate the correctness of your HA receiver output at the moderately loud level of sound - 65 dB - normally considered the level of total output relevant to speech understanding in normal conversation. According to the following, proper REM is typically performed to see if the HA receivers are capable of delivering that moderately loud output with the applied gain settings at (each?) test frequency. Basically, in situ audiometry is a test of the lowest possible output you can discern. It doesn’t test how your HA’s are performing at higher degrees of amplification at each frequency. You have to assume if the level of output you can just hear at each frequency matches a recent HCP audiogram done with calibrated instruments that all added gain at each desired frequency is working correctly with your instruments - which may or may not be a reasonable assumption: How do you know if your receiver is not working well? - #21 by jim_lewis
A Beginners Guide to Real Ear Measures (REM) (interacoustics.com)
Edit_Update: and from the main Hearing Tracker site with reference to a Dr. Cliff YouTube video: Real-Ear Measurements (REMs) (hearingtracker.com)