Audio Systems: 2001 town & country infinity system, infinity speakers, chrysler town and country


Question
I have a 2001 Chrysler town and country limited. It had a factory infinity system in it.
I’ve installed an aftermarket Sony (CDX-GT360MP) radio and had some trouble with no sound, until I did some research, to find out that the new radio was not powering up the speaker amps. So, I then wired 12v from the blue antenna power wire on the radio, to the relay under the hood (pin 87).  This now gave me sound, but The problem is, that I now have the sound cutting in and out, when volume gets around 20 (max is 50). This is by no means loud at this point, just to the level of average talking voice.
I’ve checked and double checked all the grounds and they seem good. Some of what I have read suggests, bypassing the amps at the speakers, and others, putting some sort of   hi low interface that lowers the output of the radio to match what the factory radio put out. And also some suggest rewiring and putting new speakers in. I really do not want to run wires and/or spend any more money on speakers, when this van already has awesome infinity speakers in it.
 What is really baffling me is that years ago I took the infinity speakers out of a 1996 T&C that already had an aftermarket JVC in it and installed the speakers in a 1996 Grand Caravan (that did not have an infinity system) with a similar Sony radio that I’m trying to use now. When I did that installation, I had to individually wire 12v power to each amp speaker from a switch source I found nearby. The end results:
This system works great. I love the volume and sound. So I thought putting in a similar Sony radio in an already infinity system, would be a piece of cake. But this is driving me bonkers and I don’t know what I should try next. I thought maybe wiring individual power at the speaker like I did in my caravan, but could this possibly be the issue?
 Please Help

Answer
The problem is the high output radio of 40x4 ,this input its to much for the amplifier,
also there are separate grounds for every speaker the infinity amplifier needs match ground signals,

you need the hrc-uni or the soudgate xrt4

http://www.oemautosound.com/p-99-oem-interface-differential-converters-headunit-