Using DR v1.6 hardware with IC-746 and RX audio from The 8-pin 5 of the ACC1 connector. With AGC off and the level control at 0 in W10 sound, the level indicator is just below the red level in WSJT-X and there is a significant amount of digital noise.
Is there an attenuator as with v1.9 or different driver then Microsoft 10.0.19041.1682?
Sorry, there is no hardware attenuator in rev 1.6.
However, your Icom has a MiniDin6 connector on the right side - same as in Yaesu (1200, 9600):
I would give that a try.
The 746 does not have that connector. Maybe the pro version does, but not the 746.
What is the impedance of the DR AF input?
IC-746 vs IC-746: just checked it again and right you are.
Re. impedance: Datasheet for CM108 doesn’t report input impedance, but it’s a mic input so it’s going to be in high KOhms. You should be able to drive it with pretty much any source. If you are trying to calculate its effect on your voltage divider, you can just go with the same 100K/12K as in Digirig 1.9.