@weme, I'm not sure what the exact question is and even if there is any? Your post is written more like as statement than a question.
As for the setup in #177, a single instance of REW was both generator and analyzer but of course on two seperate interfaces (not a single one in loopback). The two ADI's, one running as DAC the other as ADC, were not synced to each other and this is equivalent to having two PCs each running REW with one of the RME's attached.
The tested device is the DAC and the test condition was the incoming jitter on it's clock source and the varied parameter was the firmware.
The test level for the sine was the usual -3dBFS.
As for measurements with REW, please check out the latest version where the notch filter for THD+N has been changed to a wider one, mimicking the one AP uses.