Do you mean the iRig Pro DUO?
If so, turn off Direct Monitoring.
iRig Pro DUO User Manual, page 12 wrote:Direct monitoring
When recording an audio signal into your audio software, there is often a slight delay before it reaches the outputs of the software and iRig Pro DUO. This delay, called latency, is caused by the computer processing required to convert and record audio. Since this delay can be distracting, iRig Pro DUO provides a direct monitoring path from the inputs to the outputs, which is activated by the Direct Monitor switch.
When Direct Monitoring is enabled, the input signal is mixed with the output signal from your audio software and routed directly to both the Line and Headphone outputs. This lets you hear the “live” inputs without latency. The Direct Monitor switch has no effect on what is being recorded by your software.
When using the Direct Monitor feature, make sure any software monitoring option for direct (or “low latency”) monitoring is disabled. Disabling low latency monitoring prevents “double-monitoring” of input audio signals when using the Direct Monitoring feature.
When “double-monitoring” occurs, there will be an increase in volume and an undesirable “phasing” sound. For more details about its monitoring function, refer to the documentation for your audio software.
But I am not sure about your reference to SampleTank 4.
PS I have removed your duplicate thread.