wiring questions

1.They haven't used common ground setups for a long time.  So you won't have to worry about that.  I'm not a big fan of using hi/lo converters because of the noise it causes.  The hiss is very annoying.  I'm sure you will be adding a factory unit soon after.

2. Well you can get the signal from the rear speakers, but you still have to tap into the front speaker wires.  This is much easier to do at the factory radio, and you might as well run wire there to get your signal as well. 

3.  You can tap it into the ignition wire on the vehicle (or accessory).  That way the amplifier will be on when the vehicle is on.  The only downfall to this is that your amplifier will still be on when you are driving and turn off the radio.  That has only caused one problem that I know of, but only if you are getting the signal from factory powered speakers.  If you have the radio off but ignition on and you close a door, this can move the factory speakers you are gettting the signal from.  Their voice coil will produce a signal that will get amplified through the sub amp, then get played by the sub, which will then move those factory speakers even more, and so on.  This will produce a growing hum from the sub.

Steven thanks for the replies.  I never turn the radio off while driving. If I need to quiet things down I would just turn the volume all the way down. You think I will still have this hum?   How bad does the hiss get from hi lo converters? I really dont want to replace the factory head because it matches the dash so well.

What if I found amps that accepted hi level inputs ?  What problems do you forsee then?

Hasnt anyone done this?  Id love to hear your experiences with keeping factory heads and adding amps and subs.  All replies welcome Thanks alot. Boomer

never delt with a high low converter, i had a 98 cav, ran 3 amps and front rear speakers, subs off high level input, i used the stock deck just loved the way the deck looked and i still used tapes at the time, the high level sounded fine, no hiss ever, sounded very good till i dropped in a different deck, only thing i will say is the factory deck introduced noise into the system i had a low level alt whine, but turn the deck up 3 click u couldn't hear it anymore, aftermarket deck completely illiminated this noise, i ran a relay off the battery and tapped into the iginition wire off  deck wires, for my remote turn on as said above, only problem i had was when shutting off the car, i would sometimes i get a pop in the system, other then that it worked flawless for like 1 1/2 years

Here are a few options....

If you like the stock look and know you're going to be replacing the head unit, there are a few companies that make HU's to fit the GM opening...

http://www.crutchfield.com/cgi-bin/S-eUbzX3YJjIT/ProdGroup.asp?c=3&g=52500&s=0&cc=01&avf=N&search=

2.  If you don't like splicing the factory wiring, use a wiring harness kit from Scosche.  They sell "reverse" kits that plug into factory radios.  So pick up two harnesses.  One that fits your factory radio a la "reverse kit" and one that fits the factory wiring harness.  Then you connect the two harnesses and splice inbetween :)

3.  Like everyone suggested, pick up something that is on via the ignition or accessory lead.  Many autoparts stores sell a "Add a Circuit" jumper that you can plug into a fuse box and wire it up to the ignition/acc. buss then run the lead to the amp.  An alterternative is to buy a new amp with high-level inputs and "Auto Smart" turn on features where you don't have to run any Remote On line.

Tony