Did some new measurments to investigate why the Dante was so different.
With some shorter and easier signal path
PC with REW generator ASIO flex driver HDMI output
HDMI Input on JBL SDP-55
Dante output vol 69 on SDP-55
PC with Dante Virtual Soundcard and Rew RTA Analyzer
If i change the the following settings in RTA analyzer
FFT lenght: 8k
Averages: None
Window: Blackman-Harris 7
1 second it shows the green graph and in the next second it shows the red graph....
But if i paus the measurement in the right second and save. It look like this.
So maybe it is some interference bug in the sdp-55 that are causing this .
But the red measurment is good so hopefully it will stay that way after next firmware update
Green: THD+N: -100,9 dB [20..20000 Hz]
Red: THD+N: -123,4 dB [20..20000 Hz]