Are passive preamps better?

Tbg, thus my final comment on my post!

Several decades back, this problem was addressed by the recording/broadcast industry, for pretty much the same reasons that audiophiles deal with today. The result was the balanced line system, which is actually a standard.

The standard requires that the source (preamp) be able to drive a 600 ohm load. There are several practical reasons for this, not the least of which is that the low output impedance of the source thus has the ability to 'swamp out' the effects of the cable caused by capacitance and other construction issues. The result was twofold: not only can a preamp that supports the 600 ohm balanced line standard control the interconnect so well that essentially the quality of the cable has little bearing on the sound, but also the length of the cable became all but irrelevant as well.

The number of preamps in the high end audio world that support the 600 ohm standard without any sonic artifact (loss of bass and/or dynamics) are very few. Some use output transformers, and that is why the termination standard is 600 ohms, so that the transformer can drive a reasonable load without ringing. If there is no transformer, then the termination is less important.

If you have ever wondered why 'audio engineers' say that the interconnect cables make no difference in the sound, this is why: in their world it is true because they use low impedance balanced lines. Audiophiles can take advantage of this though, as low impedance balanced lines offer the same advantages to them- the standard was in fact created to solve the sonic artifact issues that audiophiles routinely experience.

Atmasphere, I do recall many saying that in professional applications using balanced cable the wire is unimportant. I once had the Cello system using Cello Strings and all in balance. We found to our consternation that Siltech balanced cables sounded better than Cello Strings. I have no idea whether the Cello Suite was able to drive into a 600 ohm load, but I suspect that was a design goal. Does this not suggest that there were still sonic differences? I remember thinking that I could not afford to use all Siltech.

A 600 ohm LOAD is tough! A 600 ohm OUTPUT impedance used to be normal for tube preamps, but then the tube power amp input impedance used to run 100K and up, so it was probably OK.

Solid state preamps have output impedance of 50 ohms or less, which would be OK even for a 600 ohm load.

Gregm, dpac wasn't using a passive linestage; he was using a tube preamp. It would not surprise me at all if I don't understand how impedence works. I'm a gifted dyslexic and I struggle. I go by instinct, and I'm learning as much as I can from you guys. And yes. I am interrested in how impedence works. Please tell me.
John, I understand what you are saying about vintage gear. I have heard of the Audio Research 10 and ll before.
I will read all of this discussion again to absorb what I can.
Scott Endler got back to me. The nude attenuators are backordered and he refunded my money. Meanwhile I've been researching autoformers and transformer attenuators, and I've been waiting for the cable to fully break in. I see the motive now for attempting to achive a successful passive linestage. Without the Sim, I hear the amp, as though for the first time, and it is wonderful. I also am guessing there will be a trade-off with a passive device. What strikes me the most is sensitivity. My amp's sensitivity is 1.1 volt, and the lower the listening level, the more this spec is evident. Lynne

Eldartford, 600 ohms may be tough, but not impossible. We developed a direct-coupled output, not unlike our power amps, to do the job. I think our MP-1 might one of the few preamps that can drive headphones directly as a result.

Tbg, I've had direct experience with the older Cello stuff. It doesn't seem that it was designed with 600 ohms in mind.