95 Alfa 164 ls, 07 Quattroporte exec. 07 Santa Fe.
So, after over a month with my new head unit and existing amp, I have not had one instance of no-sound. That, for me anyways, confirms that the amps are likely not the issue. I believe it is a no-communication issue between the NIT and amp. So, if you are dealing with the same issue, try clipping the red-green "12v signal power from NIT to amp) and attach that to the 12v power wire at the main harness 9not constant 12v, switched 12v). The only drawback to this is that the amp will have 12v at all times car is running, even with the NIT off. But, if you no longer have the "no sound" issue, that confirms the problem with your setup.