We have a NewTek VS4000 4Ch Skype TX system. People using Zoom from a Focusrite scarlett-2i2 USB device and other USB devices work great but are not working from the latest Skype client to our VS4000. We just did a test with a musician who had a mic and guitar plugged into his Scarlett and we could hear the mic but not the guitar. He didn't change anything and connected to one of our Zoom meetings and both his guitar and mic were working. We had him turn off echo cancellation and uncheck automatically adjust volume in Skype and it didn't help.