Hello, seems like lots of people are looking for this same answer so I try to be as much direct: 1. I use MAC + Tascam Portacapture X8 as an audio interface 2. I've plugged-in minijack headphones into the Tascam 3. I've plugged-in Tascam via USB to MAC. 4. I hear my voice coming through headphones 5. I record voice into the music program and it works fine 6. I try to playback what I have recorded - there is no sound coming through (potentiometers work but no sound). 7. There is also zero sound coming through headphones while trying play YouTube or some other files. Both Mac and Tascam are updated. There is no USB FS Mismatch between devices.