I have a Rosen Navigation/Stereo in dash unit that was installed by the dealer in a 2012 Hyundai Santa Fe with the Infinity system. It plugs into the factory Infinity amplifier which in reality is a JBL unit made for Hyundai.
Background hiss is noticeable, there is faint audio when turning the volume to zero, and the unit exceeds 102dBA at 50% volume, all indicating that the Rosen head unit is overdriving the amplifier. Rosen says no one else complains about it, so they will not do anything under the warranty. They admit that they are sending speaker level audio into the preamp level of the amp. I am going to try a speaker-to-line attenuator and have ordered the appropriate connectors and will build my own pads.
Both the head unit and amplifier have a + and - connector for each of the four channels. I cannot find any wiring information for the amplifier other than a connector pinout, but I am guessing the inputs are differential balanced, with no reference to ground. I do not know if the speaker outputs from the Rosen head unit are also differential balanced.
I assume the best approach will be H-pads with a 20dB drop. Has anyone here dealt with this kind of interface? I would like some input (pun intended) on this project.
I also have a problem where any key press on the head unit, whether a physical key or a screen softkey, results in a thump in the audio, regardless of volume level. I am guessing this may be related to an improper interconnection between the units and am hoping it will be solved by the attenuators. Has anyone here run across such a problem, or have any ideas of the cause?