Experts: Why is preamp important?


I know that's a naive question, but the real question is how important a preamp upgrade is relative to the rest of a system. I've heard the statement "a preamp owns the signal", but I don't know what that really means in terms of ultimate sound. For example, is preamp to amp like a transport to a dac, whereby most people would contend that a great dac with a cheap transport can still sound great? I've upgraded my front speakers in a HT system to B&W n803s/HTM1. I currently use a 130wpc Pioneer VSX49tx HT receiver. Obviously I can get better sound from better amplification, and I'm considering a separate integrated amp for the fronts. But the question is can I still make a great improvement using the pioneer's pre-outs to a much better amplifier? Where should I really spend my money? Thanks much. This forum has been tremendously helpful, and I'm sure this thread will do the same.
jeffkad
I am by no means an expert, but the importance of a preamplifier can be essential or superfluous -depending on the system configuration. Here’s some reviewer comments-

“Conceptually, the preamplifier is the bottleneck in an audio system. All sources pass through it, and it influences every sound you hear... surely a preamplifier, more than any other component, should be able to approximate the late Peter Walker's "straight wire with gain…. The acid test of a preamplifier, of course, is to compare it with no preamplifier at all." (John Atkinson; Mark Levinson No.326S…Stereophile - January 2006)

“Should a preamplifier be merely a traffic director, controlling the rate of signal flow and routing signals along chosen pathways while remaining neutral about what’s passing through the pipeline. Or should it also impart a pleasing flavor to the proceedings? These questions, long debated among audiophiles, are a waste of time, in my opinion. Anything inserted into the signal path will change the sound, even a passive volume control – especially if it’s unbuffered. Those who seek some mythical sonic purity should give up audio and join a monastery. Any audiophile who’s bought a tube preamplifier has decided to impart a particular sonic flavor to the proceedings. However, the same can be said of those who prefer solid state preamplifiers.” (Michael Fremer;Dartzeel nhb-18ns Stereophile - June 2007)

“I hate preamplifiers. The stupid things are the only links in the audio chain that are designed (italic) from the get-go to restrict, impede, and otherwise diminish the audio signal. Audiophiles can and will spend all sorts of money …in an effort to increase information retrieval…And then you stick a fancy electronic bottleneck in the pipeline to throw away much of what has been "gained". What's so hard about "Turn that damn thing down!" anyway? (Bruce Kinch; Bent TAP…Positive Feedback - September 2006)

“Some may think that the best preamp is no preamp at all. At some point, every audiophile I know has entertained this possibility; I certainly have - more than once. Some have been persuaded of its truth. For what it's worth, I gave up on pursuing this approach when I realized that even though reproducing music requires amplifying a signal sufficiently to drive a loudspeaker, producing music is not equivalent to merely amplifying a signal sufficiently to drive a loudspeaker. “ (Jules Coleman; Shindo Monbrison; 6Moons)

“What role does an active preamp really play in a 21st-century digital system outside of input switching and volume control? Clearly not gain. Most modern digital sources drive most modern amps to full output directly. Nor resolution enhancements. Or do you find the argument persuasive that -- lots of -- additional analog circuitry could increase resolution? Not. Common sense suggests that the best any active circuitry could hope for in that regard is utter transparency. Let's thus tally up our compelling reasons for adding an active preamp to a standard 2V-out CD player and 0.5V input sensitivity amplifier. Redundant gain. And resolution that's at best equal to -- but more likely, subtly diminished over -- no preamp at all. Bitter blimey. That certainly couldn't be all of it. Could it?” (Srajan Ebaen; "Pick your world view" - 6Moons)

“A superior and expensive linestage thus needs to justify its existence far less on practical grounds than any amp (can it drive the speakers without distortion is its foremost concern) or any source component for that matter (which is simply indispensable). A preamp becomes far more of an *artistic rather than essential proposition. … It's perhaps here where an electronics designer can imprint his personal vision of 'musicality' the most…Because interpretative freedom is greatest here, it's also where a designer's personal vision and yours need to overlap the most to be relevant.” (Srajan Ebaen; - 6Moons)
Tomcy6, for termination of a balanced line 600 ohms is the standard. By preamp standards, this is a very low impedance and many preamps can't drive that without a loss of bass, loss of signal level or both. Even though the termination is often not used, its a good idea to be able to drive it so as to be able to control the interconnect cable.