I thought you had the E70 Velvet which is very similar.
I can’t get a wiring config that gives me a decent balanced output measurement.
Using the rca out I get thd -121.7db and snr 116.4 when using PC mirroring. When I use REW to generate the tone, I get thd -122.7db and snr 117.2. This difference while not significant, is consistent over many runs.
The above is with a 5.8 dbv input signal at 6dbv fs.
If I change to 12 dbv fs of course the thd is better but the snr worse. The differences above between pc mirroring and REW remain though.
What is the optimal cable config for measuring balanced out from the dac into the QA403? I am still struggling with that.
Last question. In pc mirroring, if the QA is in Stop, but the GEN button is pressed is the signal meant to be on to the external dac?