I bet they connected the speaker outputs of the alpine to the imputs of the factory amp(not bypassing it). That would explain the hissing sound. I would also bet that you don't have to turn it up much before it gets loud. I would take it back and get them to bypass the amp... but that's just me.

Thanks for your reply and help throughout all this. I'm gonna take it tomorrow and get them to bypass the amp and take it back and wire the amp to the battery w/ the 10 gauge. Just out of curiosity what exactly is causing the hum?

I can't tell you the technical reason why it makes that sound. I have just had that experience with this particular situation. It's basically because you have an amplifier(the radio) being amplified (by the factory amp) Just makes for a bad sound quality(especially at low volumes).

one thing to try and get rid of this hiss is pull the stereo (you can keep it on the brackets and all plugged in) out of the hole and move the wiring around while it's turned on and see if the hiss changes pitch, goes away, gets worse, etc...

I was picking up some interference w/ my RCA cables and moving them to the drivers side of the empty space got rid of it.

So was I. I was told that by both Nissan and worstbuy.

So the fosgate unit has amplified outputs?

hmmmm......

Does anybody have all the specs on that stock HU?

In electronics, RF means "radio frequency". But I'm assuming that everyone means the Fosgate unit.

I doubt that.

I will put my Fosgate stock system up against any HU's internal amp. Any decent aftermarket amp will blow it away, but not some little HU amp.

You are correct in your assumption.

now you have shown your knowledge in car audio...
I wouldn't put too much up on that bet... The alpine 9835 to which we are speaking of has a much higher power rating (If you use the 10 guage power wire) than the Rockford Fosgate 6 disk facory radio, and the "RF" has a seperate amp.
Not to mention the numerous features that it has over the "RF" unit(other than 6 disk capability).
There are just too many to list.

I wasn't comparing HU's.

I was comparing my whole system vs that HU.

That's a sweet HU, but it won't hold a candle (power-wise) to my system without an external amp.

Let's do everybody in this thread a favor.

Let's go to www.merriam-webster.com and

look up RF.

Using RF for Rockford Fosgate is as ludicrous as using USA to mean "under sexed aliens". It works, but the abbreviation already has another universally accepted meaning.

edit: put question in new topic

you cleary stated that you would compare your STOCK system to any HU's(I'm assuming you mean Head Unit. Give us a freakin break with the grammar lessons we all know what we are referring to here) internal amp.
So If I am assuming correctly, I would think that you would be talking about comparing your RF(Rockford Fosgate) radio to another radio(the alpine 9835 in this situation). If I was wrong and I took what you said in its literal meaning, you would be comparing your whole system to the actual amp(amplifier) inside the alpine radio. That would not be a fair comparison since the alpine amp doesn't have speakers, wires, buttons, or a readout, so of course yours would be better...
Now if you don't have a STOCK setup then it of course it is probably better. but who cares... that's comparing apples and oranges.