I am amazed at how little people understand wiring. There is small guage wiring running from tip to tail of ANY car on the road, and it does not "build up resistance & cause noise" If you choose to ground your reciever with all your amps, it is a sure way to help PREVENT possible ground loops i.e. amp grounds in your trunk at the frame and as current passes through the metal of the body on it's way to the battery it can cause noise when it passes the ground for the reciever. Any reciever out there will not use enough amperage to need anything larger than factory wiring for a ground run to your amps. Hell, you are already sending current through a wire that distance to turn the amps on- does it "build up resistance" and stop working-no it doesn't. The reason for different size wiring depends simply on current flow (amperage) over distance. The more current flow you need to feed your amps the bigger the wire needs to be. The farther away from the battery the amps are, the bigger the wire needs to be. Your 4 guage wire would be fine for both amps as long as the run is less than about 19', or you could drop to 2guage for up to 30' or run a supply of 0/1 to a distro block at the amps and have a short supply line to each of 4 guage. If I already gad the 4 guage, that's what I would use. Most people just aren't running enough wattage to need 0/1 wire to everything and it ends up being engine bling- not that there is anything wrong with that, I am just a function first kind of dude and don't like wasting money on rediculously large wiring for a 300w x1 amp and a 60w x4 amp. One rule of thumb is, if you are playing your stereo loud, and the power wire is hot, it is too small- also make sure you run ground wire the same guage as the power wire. What goes in must come out. Electricity isn't used up inside an amp like gas in a motor. Good luck. By the way, I am an ASE certified Master Auto Technician and a Platinum certifed Honda Technician, so I know a little bit about what I'm talking about, and am not trying to bust anyones balls. I am only running #8 wire to my 75w x2 front stage amp, and 200w sub amp and they are both fine, but the run is 4guage from the battery through the firewall to a distro block, and 8 guage from there, and the car is an '04 Civic Si Hatchback- not the biggest ride in the world. 0/1 is probably overkill IMHO.Though after re reading your origional post, I see you have 2 1200.1's so I would probably run0/1 and use a distro block, otherwise you are going to have to run 3 4guage wires from battery to amps.