I have been using sox just to test. Code: Select all sox --buffer 32768 -t alsa -c 1 plughw:CARD=Device -t alsa plughw:CARD=Device No underruns Code: Select all sox --buffer 32768 -t alsa -c 1 plughw:CARD=Device -t alsa plughw:CARD=Loopback sox WARN alsa: under-run Anyone no why just changing to a loopback should cause buffer under-runs? Stuart Sent from Mail for Windows 10