Why a line preamp?

Seeing that's is all about "balance" in the end (and of course, most people's system, to be critical, are off balance in one way or another), I think there's probably not one solution to every system set-up!!! They all tend to have different requirements/needs depending.
I've heard some systems that seem to do better with passives, or no preamp from the CD out. And I've heard others that absolutely do better with an active preamp (some tube/some solid state).
Usually what you find is that most CD player outs(or other sources) don't seem to make a good enough match in impedance and such with amp/speaker combo's! Some times it works great. Usually, when the passive approach doesn't work, it's either thin and amusical, or dynamics are lacking and a bit weak (more noticable on percussion and rock and such..).
The only way to find out is to try the different approaches, and see how it works in your sytem! I'm currently using a Pass Labs Aleph L passive/active preamp, which works supeb with my solid state friendly Sonus Faber Electa Amator set-up! It's passive all the way to a point on the volume, then goes active...best pre-amp I've had for this system. However, I noticed the same preamp doesn't seem to work as well with my older Thiel speakers/Classe amp combo! The sound was a bit thin, bright, and lacking snap! That combo did best with a tube active preamp for sure!
Anyway, you just gotta try for yourself what works, then you'll know....no free lunch...

fliceswater: what a great moniker! won't you post, please, in the "who r u" thread and tell us how it was derived? -cfb

I've heard the McCormick preamp, it did not sound good in my system. I like a buffered pre-amp. See the Pass Labs website. You can make your own

The source component that sounds without preamp is THE source component of the high quality with stabilized and well engineered output. In this case you'll need no line stage at all -- pure signal, no feedback(if poweramp has no feedback), best details, open and transparent sound etc... So If you want to find out the "naked" sound of source component ask dealer to plug it to power amp directly when you audition. Phono stages aren't tended to be as stable as DACs/CD-players(unless it goes to BAT P5 or Herron levels...$4..5K) since they're working with much smaller signals and most-likely will need line stage(extra gain and feedback).