remote wiring

i know this may seem like a noob question but i just wanted to get it squared away before another amp blows. if i wire an amp into an oem head unit, where should i wire the remote wire to if the factory amp is not an option? i've wired into the radio fuse before but i'm not sure if that's a great idea. so my question is, should i wire to the radio fuse, or is there a better option aside from the factory amp?

you talking about the amp turn on wire (remote wire)? trying to wire it to a factory radio? if so, what car and what year? if it is an aftermarket radio use the blue or blue/white wire behind the radio, or the red wire that tells the radio to turn on. if it is a factory radio usually there will be a wire that has a switched 12v wire and you can use a meter to find it if you have one. though, some cars dont have this wire so if you have one of these i would try to go to the accessory wire at the ignition harness or try to see if you have a switched cigarette lighter and use that to turn on your amps. i really dont like going straight to the fuse even though there is usually nothing wrong with this, i just dont like it.

this is for a 2000 Lexus GS400, with stock navigation. I would like to avoid tapping into the factory amplifier.