Hissing in aftermarket unit

[BCoSiestaKey]

I saw a post about this but now I can't find it. 

After adding an aftermarket Android head unit there is a hissing.  Any suggestions on a fix? A new amp?

B. 

[Maduh]

Are you using the stock amp? No amp? Is there any adjustment on the headunit? Need more info.

[BCoSiestaKey]

I am using the stock amp and adjustments in the Hu equalizer don't help .

[barmato]

Assuming you're talking about an aftermarket head unit with stock speakers/amp, I think this is just a side affect of having speaker level outputs on the aftermarket HU going to another amplifier.  The noise/signal ratio is too high after being amplified twice.  Mine does it too.  The best fix is probably to bypass the stock amp and replace the speakers with "normal ohm" speakers.  Another possible fix might be to try a line level adjuster to lower the signal level but I haven't tried.  I can't really hear the hiss when music is playing.

[Chrisbee]

You'll probably need this.
It's a pre-amp line control if you're running an aftermarket head unit with the factory amp.

Scosche SLC4
Item #: 142SCOSCHE

This is from Crutchfield.

[BCoSiestaKey]

I shall purchase that, Thank you. 

[TheBigChill]

I shall purchase that, Thank you. 

Make sure you ground this guy, too.  It has a Black lead coming from.  Not doing this could result in even more interference. 

[Woody]

I'm installing a new Kenwood with the Scosche this weekend.  Seems like the way to go with the BOSE amps.

http://www.scosche.com/car-stereo-output-converter

This website has PDF instructions you can download.  Much more obvious after reading them.