Using Logitech Z-560's without control box

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My set of Logitech Z-560's recently went out on me. After talking to Logitech, they have requested that I send the control box to them and they will ship me a set of Z-5300's as a free replacement. However, the control box appears to be the part that actually went bad. I tested it using my friends Z-560's and it does the same thing. Power light glows, headphone jack (and volume control) works, but the M3D switch (and light) is non-functional and no sound comes out of the system.

I took the liberty of tearing the sub/amp apart and got out my trusty volt/ohm meter to do some testing on the connecting wires between the amp and control center. There are 10 possible connections including the outside shielding ground (green).

The brown, grey, purple, orange and yellow wires appear to be the FR, FL, RR, RL, and SUB signal wires (not necessarily in that order) along with a seperate shielding wire (large black) around them for signal ground. That leaves me with the black, red, and blue wires to contend with.

I took voltage readings from them across ground and these are the results: black -18V, red +18V, blue -mV that jumps around. Accordingly, red to black yeilds +36V, blue to black yields 17.5V, and red to blue yields +6.5V.

Red is obviously the power lead going to the control center. I was assuming that one of the other two is a signal lead that tells the amp to turn on when a current is sent through it (triggered by the control center power switch) as in a car amp. I had figured it to be the blue, but am looking for confirmation.

Ultimately, I would like to fab a basic box to turn the amp/speakers on/off with a volume control and pre-amp ins. Balance, fader, and headphone jack are unimportant. As a matter of fact, a volume control isn't critical either. Can anyone offer me some help and/or point me in the right direction?
If you need any other information I would be happy to provide whatever you need if I can. Thanks.
 
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