I would try swapping the antennas (shouldn't make a difference but worth a try) not really sure what else it could be, but I would start by swapping components and making sure everything works.

 

not sure if this helps you but heard the stock amp on the disco 2 is under the driver seat, not sure if this is the case for you but might save you some headaches if you decide to do a rewire

 

i think its there too.
so i took another radio i had, and test different setups. it appears to be an rca plug issue with what i wired up. i cheaped up/ could find locally the wire harness with the rca's in the speaker locations, so i made one. i think i did something wrong with that. i took the negative and solderd to one side and the positives to the other, for the front, then for the back, which gave me a front set and a back set. but i think that was wrong. i'm really frustrated and getting pissed off about this whole damn thing!!! i have never had this many problems...and this whole thing is making me look like and feel like an idiot!!

 

try switching the blue wires on the back of the alpine it just occured to me that the blue wire on the radio harness (the one from crutchfield) is not a power ant wire but it is a amp turn on wire, hook up the blue/white wire from the alpine to that wire and you should have dvd and ipod sound!!!!! cant believe it took me this long to realize that. that wire loses power when you switch from radio to dvd or ipod therefore turns off your factory amp during those modes I was really confused why you said you wouldn't get anything without that wire connected but now it makes sense.

 

don't feel like an idiot when it comes to amplified systems (especially these systems with comon grounds) they get confusing for even professionals, there are so many "premium factory sound systems" and they are very different. I hope you are starting to see why I just bypass the amp to begin with, intergrating just adds more components to have problems with! That and the fact that your quality of sound in the end is still coming from that factory amp and not that nice Alpine (even though you get a little more control of the sound)

 

so that blue wire off the back of the crutchfield harness i have hooked up to the antenna wire on the alpine. if this is not hooked up, i have no radio. there is another blue wire on the crutchfield harness that comes from the same slot then loops up to another spot on the harness. should i cut this wire and wire it to the blue and white wire on the alpine?

 

dont even hook up the blue wire on the alpine hook up the blue white wire in its place, the blue wire on the alpine only has power when the radio is on (power antenna wire) the blue white wire has power while the alpine is on (amp turn on wire,powered regardless of what source is playing) that blue wire on the crutchfield harness must stay powered to keep your factory amp turned on.

 

basically the crutchfield harness jumps the factory amp turn on wire and the power antenna wire together (I am sure the power antenna wire doesn't even connect to a wire on the other side)

 

It sounds like you have the power antenna lead hooked up to turn on the amp. As soon as you switch to a feature other than radio it turns off and you have no amp in the system.

 

this is where i'd buy you a drink Chris, because that fixed everything!!!!
i did have to do one thing. i unplugged the red RCA for the rear and plugged it into the sub and turned the sub port off on the back of the alpine. no alternator whine and improved sound and imaging, especially with vocals.

thank you!!