@marco1 Was that also Iris DDC 12th? The version of DDC could make a difference, I think, since the new 12th has some improvements e.g. power supply, new FPGA chip, etc. I could not compare the two DDCs since the old one is not compatible with my T+ after updating to firmware V3.7. I also remember hearing improvements over USB direct when I first installed the old Iris DDC 2 years ago, that time my T+ was running on V1.0 fpga firmware. BTW, I have clock sync set up so the DDC is using T+'s OCXO clock instead its internal TCXO clock.