How important is the pre-amp?


Hello all,

Genuine request here for other's experiences.

I get how power amps can make really significant changes to the sound of a system. And of course speakers have an even bigger effect. And then there is the complicated relationship between the speaker and power amp. But I wonder about pre-amps.

In theory a well designed preamp should just act as a source switch and volume control. But does it add (or ruin) magic? Can a pre-amp color the sound? Alter pace and timing? Could you take a great sounding system and spoil it with the wrong preamp? Stereophile once gushed (while reviewing a preamp that cost as much as a car) that the preamp was the heart of the system, setting the tone of everything. Really? Some people don't even bother with a preamp, feeding their DACs straight into the power amp. Others favor passive devices, things without power. If one can get a perfectly good $2K preamp, why bother with 20K?

What your experiences been?
128x128rols
I don't think the preamp is the heart of the system, but I'd go with pancreas for sure. 
Interesting discussion. One topic I haven't seen mentioned is how the "Line Level" of a DAC or preamp output affects the equation. When I was young, I was taught that the main purpose of a preamp, assuming you don't want to color the sound, is to receive an input signal and output an uncolored signal to the power amp at "Line Level". So, in theory, if you have a good DAC (with a good volume control and analog output section) which provides an analog output at the same Line Level as a given preamp, how could the preamp do anything BUT add coloration? But, if you look up Line Level on wikipedia (https://en.wikipedia.org/wiki/Line_level), you'll see it's not quite that simple.

To use a specific example I'm familiar with, the Gustard x26-Pro is reputed to be a pretty good DAC, and some of the posts on this site have said that it's analog output section is a good one. Yet others will say that feeding its output directly into a high quality amp provides noticeably poorer sound than using it with a good, uncolored SS preamp, such as a Benchmark HPA4. Why would that be? I don't know the answer, but I'd bet it has something to do with the DAC's analog output being unable to match the Line Level of the output of the HPA4. This doesn't make sense to me if the DAC truly does have a good output section, but I trust the people who tell me it matters to them. If anyone would like to weigh in on this, I'd love to learn more.
I took out my Ayre KX-5 Twenty a few times to test if the cost is justified. I immediately put it back in with a dCS Bartok & Lumin T2 (demo) going to an Ayre VX-5 Twenty. My experiment to omit the preamp backfired as I ended up buying an Ayre KX-R Twenty once I experienced the importance of a good preamp. It doesn't matter that the Bartok has a 6v balanced output. I wouldn't consider running raw dog unless I had a MSB Select II like @mikelavigne.
A good pre-amp just like a good DAC should be essentially transparent.  A bad pre-amp just like a bad DAC can poison a system.
Preamp is like Salt & Pepper added to food. My theory has always been:
40% Speakers
30% Amp
20% Source
10% Preamp

Not all preamps work the same for all amplifiers. I have NAD1155, Emotiva PT-100, Schiit Freya +