Should I Set My Audio Interface Input Gain at +4dBu or -10dBV?

Some audio interfaces have adjustable input gains which can be accessed in their control panel. For example, an RME Fireface UC:

As a general rule of thumb, use -10dBV input gain for low level signals and +4dBu for higher level signals. Using -10 makes the most use out of the headroom and signal/noise ratio, and switching to +4 can help avoid clipping if the signal is high level. You can always create two different calibrated channels in SoundCheck, one set to +4 and one set to -10 and use them when applicable.

If you purchased a device with adjustable input gain through Listen, the calibrated data spreadsheet will include the input level used in it's naming scheme (for example, "FF UC +4dBu SN"). If the input level is changed, the device must be manually calibrated to find the correct Vp values for the new input gain.