You're using an 8ga wire with a little 10-20amp fuse attached to the wire running from the battery to the amps, right???
Here's a list of things you're going to need...
Go to your local car stereo shop, and you're going to buy 20ft of 2 gauge wire
a Street Wires FHXL fuse holder
a 100 amp ANL fuse
A Street Wires fused distribution block like this one:
A Single distribution block
get about 12ft of 4 gauge ground wire (you'll use about 6ft of that from the block to a point in the trunk and the remainder of it, cut in 2 sections, one for each amp's ground connector.
Get about 20 ft of remote wire (16 gauge blue coated wire) for the remote wire connection from the head unit to the amps.
Now for the install tips and reasons why I listed the equipment I listed....
It is always a good thing to have a nice gauge wire going from your battery to your amps, especially if you're running more than one. 2 gauge or even 1gauge wire will ensure you get plenty of power to the amps.
The fuse will be strong enough that it will be there to protect the equipment. I had a 60amp barrell fuse before with 2 amps and it would sometimes pop, so I put an ANL style fuse holder with a 100 amp fuse and it never popped.
Assuming you have used a wiring harness to the car from the sony, don't forget to use the remote lead from the head unit and use the blue wire to run it to the area where the amps are (trunk perhaps?) run the remote wire from the head unit straight into the 4ch amp cut another piece and plug it into that same remote connection at the rockford and from there, run it into the other amp's remote connector, you're done with that for now.
The reason why your battery got drained is because you hooked up the power to the amps straight from the battery and even though your stereo was off, the amps were still turned on and sucking juice from the battery b/c they were never turned off to begin with. Once you connect that remote lead to the amps, everytime you turn the stereo off, the amps will shut off also and your battery will be fine. Also, remember to turn your volume down to 0 everytime you turn your stereo off, that will prevent the speakers from emitting a popping sound accidentally since the amps will be turned to a certain gain.
If you're interested and would like to simplify things, street wires makes a 6ch rca cable in different lengths, so all you have to do is run a single wire to the trunk and it has 6 heads on each end, that would cover your speakers and the subs as well from the head unit. Now, don't be confused when I say "speakers", what I meant was connecting the audio out channels from the head unit to the amps to bypass the radio's built-in amp.
If your head unit doesn't have front, rear and sub out connections, you may have to use a y adapter for the front connectors so you can amp both front and rear channels. Keep in mind that if you do this, you will lose your ability to fade the front and rear channels.
You will still need speaker wire from the head unit to the amp for your fronts and rears. You will need 4 pairs of 16 gauge speaker wire and run them from behind the head unit to the amps. If you have already done this then, the install should be done.
Let me know if you have any questions.