I had question about the remote wire on amp. I have factory HU on my car and I'm not sure if it have amp remote wire. and if not can I connect the wire to power antena wire to do the job? and if I use either of the wire doe it mean the amp will the turned off when I turn off the HU? I know this probably seem silly for all of you who know about it, but I would like to find out before I do this.
actually, check the amplifier's manual. if you use the high or speaker level inputs built into the amp, it may support 'auto-on sensing' that turns teh amp on when it senses a signal on the input wires from the radio, requiring no REM wire to be used.
If it doesn't do this, you don't want to use the pwr antenna line on the radio as that only sends 12 volts when the radio is on, and not the CD or tape. Use a switched ignition wire for the REM trigger, thus the amp will turn on when the keys are in and turned to ACC or START at the column. that's the best way I could suggest to wire an amp to a factory radio.
PAC Audio also makes some excellent "trigger sensors" which sense the voltage on the speakers and will trigger the remote wire on the amp. Good product, I bought one to put in my friend's Taurus. He had two amps, one for the subs and one for the speakers, I split the output of the trigger wire and ran one side through a switch and to the sub amp then ran the other side directly to the speaker amp. Now he can turn off his subs if he is driving somewhere and wants them off.
Just use the power antenna wire if you have it. That way the amp will only come on when the HU is turned on and save power (gas and amp life. (The remote just needs a constant ~+12 volts to hold the AMP on).
Note: You can place a switch in the line and place under the dash or on the driver's side door. That way you can manually turn the amp off if needed.
You'll need to test your head unit to see if that's true with yours. All the head units I have had send 12 volts any time the head unit power is on regardless of mode that it's in (CD/Tape/Radio etc). If you have a power antenna and its up all the time regardless of mode then your fine.