XLR to RCA Adapter Dilemma

There is no way to provide a definitive answer without knowing how the output circuits of the preamp are designed. But it is certainly plausible that the sound could be significantly different for the two connection arrangements, for reasons that have nothing to do with the adapter itself.

I would expect that in many and probably the majority of designs there would not be a significant difference between the two configurations in the voltage seen by the power amp, because when using the preamp's balanced output in conjunction with an XLR-to-RCA adapter you are only utilizing one of the two signals in the balanced signal pair. In many (although certainly not all) situations where a volume increase such as 6 db occurs balanced vs. unbalanced the voltage of each of the two signals in the balanced signal pair is the same as the voltage of the unbalanced output. But since the two signals in the balanced signal pair are inverted relative to each other (i.e., 180 degrees out of phase) the DIFFERENCE between them at any instant of time, which is what a balanced receiver circuit would respond to, would be twice as much as the voltage of the single unbalanced output signal of the same component.

Do you tend to set the volume control at about the same positions in the two configurations? If so, differences in voltage are probably not the explanation.

Another possibility is simply that the output stage which drives the two signals that are supplied to the XLR connector may be independent of the output stage which drives the signal that is supplied to the RCA connector, and may have significantly different design characteristics, including output impedance among many other possible differences. As I say, the question can't be definitively answered without being familiar with the internal design of the preamp.

In saying all of this, btw, I'm assuming that you are using the same RCA-to-RCA cable in both cases, and when you utilize the XLR output of the preamp you are using an XLR-to-RCA adapter at the preamp's output. As opposed to running an XLR cable from the preamp output and using an adapter at the power amp input, which would introduce additional variables into the mix.

Regards,
-- Al

Liz I believe that the less stuff in the signal path rule is pretty much accepted as a truth. I realize that it does represent a theory or tenet of a widely held belief system that many audio people ascribe to. I also know about your
"tube buffer" work around, which flies in the face of this sentiment.

"I believe that the less stuff in the signal path rule is pretty much accepted as a truth"

Well, the simple old game of rope pull debunks this myth, The more that pulls the greater the result.

Thanks Al, for always supplying enlightened and reasoned answers to this forum, we need more guys like you.

Good Listening

Peter

Thanks for the responses, folks. Yes, Al, I am using the adapter at the preamp out only, and then plugging into the power amp directly with the rca. Also, I am using the same rca to rca cable. I have a/b'd this ad nauseum, and my ears continue to conclude that using the adapters through the balanced output of the preamp results in greater clarity and volume over the rca to rca connection. To be certain that it just wasn't "me," I had my wife listen to the system and she came to the same conclusion.

Also, to Elizabeth ... thanks for validating that practical application can trump theory. For a minute there, I was beginning to doubt myself because the theorists maintained that what I was hearing was simply impossible. I feel much better now.