It said -10 to +50 for line input on Audient's page. So when you have the knob at 0 you may in fact be attenuating 10 dB?
Ok I found it. It says mic gain 0-60 and Line gain -10 - 50db. Even like that I'll have +10db gain which will make it -8db at max. Which still is strange to me. The V-twin mesa preamp would peak the line input at its maximum volume.