Logitech Z-5500, whats impedance?

I checked out all the specs before it but what still puzzles me is two things:

- Signal to noise ratio: >93.5 dB, typical 100
- Input impedance: 8,000 ohms

Whats signal to noise ratio
And what is Input Impedance? 8000 ohms seems a hell of a lot compared to all the other speakers I had a look at.

Generally in audio and hi-fi, the input impedance of components is several times higher than the output impedance connected to them. This is called voltage bridging or impedance bridging. In this case,

Zload >> Zsource

In general, this configuration will be more resistant to noise (particularly power line hum). The best circuits are created by using a voltage follower in the source with the pull-up (load) resistor at the signal receiver.

So a 8000 omh input impedance is how hard the humm will have to work to get in

basically...the difference from the signal (though it's not that simple, as margag_ noted...let's just say the signal is music) to the noise inherent to the speaker.

for your purposes of buying speakers, noise is the "hissing" you hear when your speakers are turned up loud but have nothing playing over the speakers. the fact that electricity is flowing through the circuits in the speakers guarantees some sort of noise. so if at a given volume the noise is quieter and your music is louder, that is the higher the signal-to-noise ratio, the better and cleaner the sound...makes sense, right?

High impedance doesn't actually tell you much - the speakers have a separate amplifier, so it's mostly just a meaningless spec.