150a would do just fine... put it at the battery end.
search; Blue Sea Systems MEGA/ AMG Fuses
I purchased a DC Audio 175.4, which does not include an onboard fuse. They recommend using a 140 amp fuse, although these can be difficult to come by. I ordered an Absolute brand from Amazon because it was the only place I could find it. Are they a reliable brand? Also, would a 125 amp fuse be sufficient? That and 150 amp are both readily available, however, I'm hesitant to use the latter. In case I add another amp, I'll use 0 gauge wire. Are there any fuse brands you should avoid?