I seem to get a very slight hiss in the background while playing a CD. Does anyone else get this? It is only noticeable when the song gets quiet but it does increase as i increase the volume so at high volumes it gets quite noticeable during a quiet part. And to anyone that has done the silent beeps mod do you still get a little bit of a sound when clicking buttons at low volume levels? Just asking because i wasn't sure if i had a bad silent .wav file or if that is normal.

there is nothing you can do about this, other than keep the audio levels down.

I dont know the correct terms, or why exactly it happens, but I do know what it is.

I had the same thing happen, and it was because I had all stock stuff, Speakers and stock amp. I have since then upgraded to all new componets all around the truck (2 sets), an amp to power them, and a AudioControl EQS equalizer. With the EQS, i can adjust the pre outs to give me more than the normal 2.2v pre outs the F900 gives me, but if i completly max out the gain and the other power options i have (I dont have it in front of me and dont care to look) ill get a slight hissing sound, I just tune it down a little and it goes away.

So long story short, its just feedback from your HU, and the signal its sending to your speakers.

Interesting But i have amped component speakers up front too and my previous pioneer unit(DEH-7800) with 5 volt outputs gave me zero hiss. Could this be from me going from 5 volts down to 4? I haven't even changed the gain setting on my amp either.

Thats possible, turn down the gain while everything is on and see if the hiss goes away at the same volume. Right now im getting a little hiss too, the EQ is located under the front passenger seat and i just havnt gotten around to turn the gain down and get rid of it.