Your Amps have a DF of 1,000. That's a lot.
As you use monoblocks, they can be located very close to the speakers.
If I would be in your shoes, I would look for two pairs of 4" copper solid bars (round) and stuck it into the binding posts, when the Amp and speakers are facing back to back.
For a long cable as 2.5m long, you need 2x 0 AWG! a 5m long is 4 x 0 AWG!