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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
bpoletti
1,553 posts
 
I didn't read most of the comments, but looked for a key word that seems to have been overlooked.  IMPEDANCE.  A preamp is the heart of the system.  It receives musical signals from a variety of sources, often with widely varying output impedances.  The preamp selects the input, manages volume and balance control and outputs the signal to the amp(s) with a single output impedance to drive the amp(s).  

Because the source devices can have a wide variety of output impedances, it is important for the preamp to have a high input impedance.  And to drive a wide variety of amps including those poorly designed amps with low input impedance, it is important for the preamp to have a low output impedance.  
itsjustme
682 posts
 
a key word that seems to have been overlooked. IMPEDANCE.
Actually both MillerCarbon and I went into it.  I did very specifically.  And basically, yes, a hgih output Z and low input Z is a bad combination. Plus some (very long) cables may have some issues being driven by a high Z output Z due to capacitance.

itsjustme
682 posts
 
... should have continued.  But a DAC **can** have a solid, low-output impedance.  That doesn't mean they all do, or that they are all good ( the vast majority of chip opamps, sigh).  So again, there is no right answer, no simple answer. You need to look into what you have, and evaluate if its lacking. Sorry, math.
atmasphere's avatar
atmasphere
11,841 posts
 
I firmly believe that for 99% of applications, a true, discrete, stepped attenuator using a minimal number of resistors, great contacts, and good (not awesome) resistors is pretty darn transparent.
It is.

The thing that is keeping the preamp as a thing in high end audio is the simple fact that most sources don't have the ability to handle the interconnect cable used all that well. A good preamp does. A preamp that colors the sound more than a passive control isn't a good preamp in my book. A good preamp will be less colored than a passive. This is simply on account of the interconnect cables themselves (if you've ever heard differences between cables you know what I'm talking about). Cables will exhibit the greatest amount of coloration with passive devices.
dsper
663 posts
 
@larsman
When I added a Herron Audio tube pre-amp to my system, it was an immense change, and all for the better.
I have been thinking about a Herron preamp.

Why is better than what you had? What did you have before? What's the rest of your system?

Thanks for listening,


Dsper
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