opinions on adding fm mod wiring, etc

I will be installing an FM modulator in my car so I can listen to my portable DVD player and my Mp3 player (found it in storage -big 'ole 64meg. Oh, yeah! I can fit like 10 songs on it -whoo hoo! lol. I was one of the only people in HS to have an Mp3 player in '04, I was pumpin'. Ramble, ramble. Blah blah blah) through my HU. It is the wired-type, where you insert the antenna plug and then plug another from it to the HU. -This isn't considered a modulator, is it?

Anyways, it needs to be wired to 12v and ground (no problems with lack of SQ due to low battery power!). It has like 14g power and ground leads coming out of it. Where could I tap into for power ('95 Cavalier)? What should I fuse it at (was going to do 5amp, is this sufficient?). Should I have it on a switch or relay (controlled by a switch) or have it on with the HU at all times? On with the ignition? This is what I need advice on.

Thanks, Javin.

Yes it sounds like an FM modulator to me.    When you remove the radio to connect the antenna wire, look at the harness that plugs into the back of your radio.  There are 2 yellow wires in that plug.  The yellow wire that is located near the orange wire is the switched power source for your radio.  You should connect the power wire for your modulator to that wire.  The wire is fused in the fuse box of your vehicle.  But yes a 5 amp fuse will be fine.  Without knowing more about the modulator I can not answer the switch question.  Some of them have audio sensing switching that will turn it on and off when it sees audio.  If you do need a switch, you DO NOT need a relay. 

All of the above typing and never looked at your name.

Don't you have an AI-Net Alpine deck?   Your deck is capable of an audio input via a KCA-121B  20 bucks from your local Alpine dealer.  I think Alpine is currently out of stock but there are other manufacturers

Well, I have my HU wired directly to the battery (red and yellow wires twisted together, and ran to the battery via 15a fused 12g). But I guess I can use the yellow (switched) wire from the factory harness. Didn't think of that! Thanks!

Yes, my HU is Ai-Net capable. Why do you ask?

An FM modulator should be a last resort.  You have an AUX in built into your deck.  All you need is the cable and go into the menu and turn AUX-IN on  default is off.

Oh, right. It's just one of those "I already have this and I don't want to spend any more money" types of things...

Will it added undesired noise? I'll look into the KCA-121B, though.

Are you and DYohn the only 2 guys helping people out here? J/K, keep up the good work guys. ;)