Preamps for dummies that would be me

In fact, it's all about the system's integrity.

Yes, basically the active preamp is designed not to only bring the signal to the line level but to restore drastically compressed and feedbacked output of the cheap CD-player with bi-polar output stage for example and bring it to the amp that also has quite large amount of feedback.
A good active preamp is usually built with small amount of feedback and can be a great interface between the components. The output impedance of preamp and input impedance of the poweramp have to match approximately 1:1000
Most-likely all active pre-s have a low output impedance that can match well with low input impedance of the SS amps. The low input impedance of the amplifiers is caused by deep negative feedback that highly limits the input sencitivity.

No, no active preamp shall be designed to 'condition' the sound but in fact they do despite being designed not to.

Yes, if you have invested into the high quality source component CD-player or analogue; if you have low neg. feedback on your poweramp, high input sencitivity all you need is just input selector and volume control i.e. passive preamplifier.

Just of the tech experience I can add the following:

Any preamp that is using variable electronic or op-amp feedback with bi-polar high-gain output stage will certainly deplete and compress the sound drastically. The sound change is very similar to turning-on Dolby NR system to the cassette or any tape as you plug in such pre- between your components v.s. no preamp.
The same amp with regular R/C feedback tend to colour the sound and make it extra-bright due to high instability of the bi-polar elements.

So choose either tubes MOSFET or JFET preamp that most-likely have low neg. feedback, linear and does only minimal 'conditionings' to the sound.

First, I have to disagree with Marakanetz about the output/input impedance ratios - a preamp output impedance to power amp input impedance ratio of 1:20 or higher will be sufficient. (For instance, if your preamp has a rather high output impedance maximum of around 1,000 ohms, try not to pair it with a power amp having an input impedance below about 20,000 ohms. As a practical matter, most preamps have an output impedance lower - and most power amps an input impedance higher - than in this example, so impedance mis-match between preamp and power amp is not usually a problem anyway). Also Marakanetz, what are you talking about with your references to preamps having to "restore" the "drastically compressed and feedbacked (sic)" output of CDP's? This makes no sense to me at all.

Randalle, the basic answer to your question is gain: active preamps offer additional gain, which might be needed to listen at the desired loud volume, depending on the source material, the source component's output level, the gain level offered by the power amp, the speaker sensitivity, and the size of the listening room.

Also, controlling volume with a passive device can sometimes become problematic due to impedance-matching issues between the resistive element used for volume attenuation and the impedance characteristics of source outputs and amp inputs, as well as those of longer cable runs. Active input and output buffering around the attenuation device, as in an active preamp, can eliminate these potential issues, which can make system matching easier by providing volume control that is relatively insensitive to surrounding conditions, and by relieving the source component from having to drive long cable runs.

Ideally, a preamp could provide gain only when it is required, but most active preamps have a fixed permanent gain factor, which is then attenuated as needed by the volume control - often (as you note) to levels below that of the source's own output level (AKA below 'unity' gain). Generally speaking, the less gain - and the less attenuation - applied to the source's signal, the more transparent the sound, so passive attenuators can have a theoretical transparency advantage for sources with sufficient output drive, as long as none of the above-mentioned impedance-matching difficulties arise. (Click on my Threads and go to the one about preamp bypass testing for more related to your question.)

For most people who are just starting out into audio think that preamps are not terribly important components. Their purpose is to regulate volume. How hard can that be???

Well, I will tell you it is a lot harder than you can probably imagine (at least doing it really well). There are quite a few good speaker, amps, and sources in the world... HOWEVER, there are far fewer good preamps.

A wise audiophile once told me: 'Any given music systems signal has the most chance of being screwed up by preamplification.'

Well it is passed my bedtime...

KF