the 1608 (wich one do you have, the DX or the AB?) is an analog to digital converter
and the direct connection via USB is a digital to digital connection
the stagebox has analog preamps before the converters to adapt (amplify) the analog signal to the right level for the converters
but this could be the problem in your case
if the overall level of your signals differ then your gain settings in one of the devices is away from the needed gain
if u are using a click signal use this as gain reference
since this is mostly a generated signal and is consistent over time you can send it out to the SQ directly (USB)
note your level at the meters
then connect your stagebox and bring up the gain to that level where your click track reads the same level on the meters
of course you can save your settings to a scene
but Petra will already know that
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