Are there any fuses showing in the side of the 2 Amplifers ?
If not check the specs in the manual or check the website.
If so add up the fuse ratings and fuse your wire for 10 amps extra.
Amplifer #1, has a 30 Amp fuse
Amplifer #2, has 2 x 40 Amp fuses
Add the fuses together from the 2 Amplifers (30 + 40 + 40) = 110 Amp draw
Also you have to fuse your power wire so that it can not exceed the max power handling limits of the wire.
8 Gauge wire can only handle a Max of 100 Amp draw (before the wire gets to hot) over an average of 20 - 25 feet.
See this link & look at the table on the bottom right corner:
This is why fuse blocks are nice because you can fuse the main power wire for close to the max, and fuse the amps individually at the fuse block just before the amps.
Hope this helps,