In an attempt to clear up this confusion, I did a quick google on 'line level' to provice some definitions. Every single one of them uses 'line-level' to refer to unamplified, low level signals typically sent over RCA cables.

http://www.audiovideo101.com/dictionary/dictionary.asp?dictionaryid=296
http://www.audio-technica.com/glossary/
http://www.strathfield.com.au/glossary.asp?Index=L&glossid=529
http://www.av-receivers.com/electronics/av/receivers/av_receivers_jargon/jargon111.htm
http://www.libertycable.com/support/images/www8.pdf
http://www.delback.co.uk/pcaudiofaq.htm

There hundreds if not thousands of other examples to show that:
line-level = low-level = RCA-level = preamp-level

Line-level never means speaker level except when in the phrase 'speaker line level'

If you see a media source device such as a car head unit offering 'line-level' output, it is always referring to low-level output.

If you see an amplifier offering line level input (pretty much all of them) this means low level input.

99.9% of electronics manufacturers and audio publications use line-level as a synonym to low-level.

[quote:bbf2718d2a=" "]99.9% of electronics manufacturers and audio publications use line-level as a synonym to low-level.[/quote:bbf2718d2a]

This statement is not accurate and this differing usage of terms in the industry is exactly the reason why so many people are confused over this. I could offer just as many links to url's with the opposite examples.

As stated in many of my previous posts - preamp level should be thought of as LOW level. These are generally represented as RCA style connectors that are meant to provide signal to an amplifier - they do not carry enough current to run speakers without some sort of amplification first.

Speaker level leads - ones that connect directly to speaker terminals - should be thought of as HIGH level. These are signals that are produced by a separate amplifier or a small amp built into many aftermarket head units. In other words an amp takes a "low" preamp signal in and amplifies it to a "high" speaker signal out.

Some head units offer either one type of leads or the other - some head units offer both.