technically you can run at853 > mv-100 > ad-20 > jb3 but there are two preamps in that setup
if you want to drop the mv-100 for a straight powering box, the ps-2 is popular.
if you want to get rid of the ad-20, you can just use the adc in the jb3.
or dump the ad-20 and get a different adc, like an sbm-1