'99 A4 in dash stereo installation...HELP

I have swapped out the factory stereo with a new Kenwood eXcelon X579. I spent all day on the phone with Crutchfield trying to get this to work. The
front speakers work fine, but the rear speakers are barely audible. Crutchfield says I have everything connected correctly, but I think I'm missing something. The car did not have the Bose system in it. I have an OEM-2 converter for the rear speakers, because I was told there was an amp for them. Any help would be greatly appreciated. TIA.
Gus
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If your car did not come with the BOSE system, then your speakers are not amp powered.
Disconnect the front wires that you are using for the front and connect them with a long cable to the back speakers. If this sound fine, then dont use the adapter go direct to the speaker blades on the speakers. Try it out.

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Thanks for the reply. Here's what the problem was: Crutchfield told me to run the L+/- and the R+/- for the rear speaker into the input of the OEM. Then, connect the L and R (positive only) wires from the OEM output to the L and R positve wires in the car. He then told me to tape off the negative L and R wires from the OEM, stating I don't need them. He then told me to ground the L and R negative wires in the car. This did not work, obviously. I then connected the negative L and R wires from the OEM to the car and it worked When I told Crutchfield this, they seemed stumped for some reason.
I thought about bypassing the amp and running wires directly to the rear speakers, but since it wasn't my car and I didn't have any type of manual on how to remove paneling, I thought I'd better not.
Thanks again.

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