Yes. The MOD Duo definitely can be used for a Bass.
The two main reasons for an analog pedal to be targeted tot he bass are:
1 - different electrical responses and behaviours
2 - different frequency range
We tackle item 1 by having an advanced analog adjustment in the inputs - based on 3 different selectable preamps plus a +12/-12 fine gain - that enables the musician to adjust the levels to virtually any instrument before going into the digital domain.
Item 2 is kind of indifferent from the MOD perspective. Most of the effects that suffer from this problem are due to the frequency range. In our platform the frequencies are normally the entire audible spectrum and, when assembling the pedalboard, you decide the range you want to use.