So I want to connect my mp3 player(iPod) to a big sony speaker I found, I think it was used for a car.
Anyway, I read that I need an amp. to connect the mp3 player to the speaker. The speaker has 2 wires.. do I connect them to the amp directly, then to the audio jack of the mp3 player? Also, do they sell those audio wires that enter in the mp3 player, because the speaker wires are separated.
If you have any info, just reply here, and sorry for my english, I dont know how that thing is called that enters in the audio jack of the cdplayer/mp3 player.

Ok a little something you need to know about audio:
Your iPod (nor any reading/portable device) will not be able to provide enough power to the speakers, you need to have your iPod connected to your amp (amplificator) as the audio source, then your speakers to your amp. Try to find out what are the speakers' power, and then buy / try to find the amp accordingly.

Hope that helps!

So this is what I plan to do:

Ipod ---> 1/8 mini to RCA cable adapter ---> connected to an amp ---> connected to the speaker.
Is that okay, or do I need another power source?

I guess this will drain the battery a lot faster, right?

Simplest way: buy amplified speakers designed for just this purpose. Electronic stores have many to choose from. This way the impedence matches through the whole chain.

I would guess you can feed the O/P of your player to an amp OK. I know you can go from the amp to passive (non-amoplified) speakers no problem. That is how the amp is designed. It is just getting the impedence right on the input side.

It will drain the battery no faster than feeding earphones, all other things being equal. The amp is doing the work, not the iPod.

What you need is an ordinary hifi component amplifier (everybody makes these), a 1/8 audio to twin RCA cable and a power source. Plug the 1/8 jack into your iPod, the RCA side of the cable into an input (not the Phono input, however) and the speakers into the amplifier. Next, turn the amp volume all the way down and the iPod volume to about half. Lastly, slowly increase the amp volume until you get the volume you want. If you have to increase the amp volume past half it's scale, then increase the iPod volume and reduce the amp volume.

Your iPod battery should last longer this way, as the input impedence of the amplifier is several thousand ohms, compared to about 30 ohms for your headphones. What this means is that it takes less power to pass the signal to the amp than it does to make sound come out of your headphones.

It can be a problem to mix home audio and car audio components. Car speakers generally have fairly different inpedence than home speakers. They do that because the voltage available in a car is fixed (12v dc).

If you are able to get an amp that will drive the speakers proberly, it will be ok. If you don't match them up, at best it will sound like crap. At worst it will destroy the speaker, the amp, or both.

Correct. Car speakers are generally 4ohm while home speakers are generally 8ohm.
The vast majority of home audio amps are rated for 4-8ohms. The best bet is to look at the amp's data sheet or the plate on the back. If it's happy playing into 4 ohms it will sound fine with care audio stuff (except really big subwoofers, which might be 2ohm).

I have in a pinch just connected a portable to speakers directly. The speakers were fairly efficient (93 dB/1watt/1meter). If the portable was good for 30 mw that is roughly 15 dB down from 1 watt, so 78 dB which isn't hugely loud, but listenable.