For what it's worth. I have run JT65, FT8 and WSPR from WSJT-X using my K3 #00345 fitted with the latest K3s digital I/O module. PTT mode no problems. The USB port is handling everything, audio, CAT (PTT and band switching). When using Logger32 for CAT, RTTY/PSK audio, software CW, again it's all over the USB cable. Regards, Mike VP8NO