The audio signals for the USB audio are processed with additional headroom, to prevent the sound from distorting at louder output levels. Due to this, the output levels for the USB audio may sound low, depending on the settings.
-The AC-22LX output level also changes according to the equalizer and effect settings.
If you’re uncomfortable with the difference in output levels, use the mixer feature of the AC-22LX Editor to adjust the output levels for the USB audio.