12-17-11: IrvrobinsonWell, not from my practical experience. Years ago I had a Benchmark DAC1 w/PCX mod and in my system, the $140 BNC Stereovox XV2 surprisely crushed a Kimber AEB/ESU in $1K range and DH Labs AEB/ESU in $300 range. It's a long time ago so don't remember the model#s.
As long as the cable has proper impedance and reasonable capacitance the XLR design wins hands down. You can buy the best solid silver RCA cable half an inch thick and compare it to any cheap-o balanced cable you can buy in a music store and the XLR to XLR signal transmission will be superior. For short distances, like less than 15 feet, the difference is often not important or audible. Balanced cables use differential signalling, which puts the portion of the waveform below the reference voltage on one conductor and the portion above the reference on the other conductor, with a common ground. That's why you see three pins in an XLR connector.
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So, will a well executed RCA design with a reasonable cable be better than a poorly executed balanced design? Yes, of course. But otherwise balanced cables are the way to go.
Later I tried a Zu Ash AEB/ESU and it was the best cable I've heard in the system.
Theory is one thing but design / execution of the design is another.