Ah, the “Overbridge is not loud enough” topic 
There has been a lot of discussion on this already: Overbridge much too quiet? (nope: just plenty of headroom) - #2 by redrabbit
In short: The outputs are 24 bit so you can safely boost each track in your DAW to -12db or so for further mixing. The outputs are deliberately so low so in case of filter / distortion peaks there will be absolutely no (unintended) clipping.