This applies to the ISA Two

To calibrate the meters on your ISA Two to your DAW, follow the instructions below:

1. Send a test tone to the line input of ISA Two. This can be achieved using the tone generator in your DAW, and the line output of your interface.
2. Connect the line output of ISA Two to a line input of your interface.
3. Monitor the input level in your DAW, and adjust the gain of ISA Two until the DAW input level reads 0dBFS.
4. Adjust the calibration knob on the rear panel of ISA Two until the ISA Two's meter value matches that of your DAW.

The meter on ISA Two has an adjustment range of +16 to +24 dBu = 0dBFS. If the maximum input level of your interface falls outside this range, you need to calibrate your system with an offset. For example, if your interface has a maximum input level of +14 dBu, you need to calibrate the meter of ISA Two so when it reads -2 dBFS, its output level would actually correspond to the maximum input level of the interface.