Man what I said above is that get a 35 mmsq copper wire it will be for Rs 700 to 900 only for 6 meteres... this will bring down the overall cost .
the above wire can easily handle your two amps so from the battery to the 2 ch amp as it will take huge load and from that amp connect the 4 channel with a thin wire take 8 ga as it will be sufficent.......ground the 2 ch amp with 4 ga wire and the 4 channel as it will be running mids and highs with a 8 ga....
U dont nee a distribution box at all....
or u can do one thing ....
here i am using two 4 ga wire to connect three amps u can use the same but single wire to two amps....simple and yet effective....here I have used thimble to crip the wire so that no loose connection is there and then bolt the thimble for a tight connection.....after that I wrapped the whole with a FRICTION-INSULATION TAPE it is a black color cloth tape used to cover any loose wire.....cost of the tape is Rs 80 for 20 meters...easily avalable at any good electical shop....the cost of thimble is Rs 14 each....no do the costing your self......lol