spot on souljah.Up to step 3, u r right.And then u have to follow ur own alternative to ur steps 4&5, i mean from dis block to both amplifier with fuse.NO WAY U CAN DO IT WITHOUT FUSES UNTIL OUPUT WIRE IS OF SAME SIZE.
I highly recommed u to go to
www.bcae1.com and read about fuses,page14.Infact they have mentioned change of size of wires the need of fuse.
LBM,u r talking about those fuses which we need even when we dont need dis.block but u dont have for changing the size of wires.As pointed by above website[and by gunbir in prev post,i cud lead to some fire hazard]
this is what
www.bcae1.com has to say.......
In the next diagram, things get a little more complicated. As you can see, wire 'A' is used to deliver power to the distribution block. Wire 'A' is of a large enough gauge to power both amplifiers. 4 gauge wire is commonly used as a main power wire. Fuse 'A' must be rated to protect wire 'A'. Any fuse rated at less than ~150 amps is sufficient to protect a 4g wire and the vehicle (if the 4g wire is longer than ~15 feet long, you may want to limit the fuse to ~125 amps). Again, fuse 'B' protects wire 'B' and fuse 'C' protects wire 'C'. Wire segments 'X' and 'Y' MUST be as short as possible because, unless they are of the same gauge as wire 'A' (or larger), they could be a fire hazard. 
In most cases, the wire size is reduced at the point of distribution. ANY time that the wire size is reduced, you must add a fuse in the line (at the point of distribution) to protect the smaller wire. Look at the following for more detailed info about changing wire sizes.