In this particular case, per my second post in the thread it appears very likely that the RCA output of the CDP is provided with the same signal that is provided to XLR pin 2 (the non-inverted signal in the balanced signal pair). Assuming that is the case, there would of course be no difference in impedance or any other signal characteristics between those two points. And if an adapter cable is used, XLR pin 2 is what would be routed to the RCA input of the preamp.
A lot of components which provide both RCA and XLR outputs are designed that way. And likewise in many cases for components which provide RCA and XLR inputs. In many of those cases involving inputs the center pin of the RCA connector and pin 2 of the XLR connector are wired together, and a switch is provided to ground pin 3 of the XLR connector when the RCA input is being used.
In some other designs, though, separate and independent driver or receiver stages are provided for the RCA and XLR connectors. In those cases, of course, impedances as well as overall sonic performance can differ in either direction depending on the specific design.
Sunnyjim 11-21-2016Are you sure about that, Jim? I’ve looked at the manual and at several rear panel photos and the only switches I see are one that turns the player’s digital output on or off (the digital output is provided on an XLR connector, as AES/EBU), and a switch that selects between "measure" and "listen" modes.
BTW, there is a toggle switch on the back of the Ayre CD player that offers either RCA or XLR connectors.
Best regards,
-- Al