Bdp24, re your question, arcdb.ws provides schematics for a number of older ARC preamps. It appears that in cases where the internal signal path is balanced but outputs are provided on RCA as well as XLR connectors, the Ref 2 being an example (click on the schematic thumbnail at the bottom left of the page), the center pin of the RCA connector is wired directly to XLR pin 2, and is thereby provided with one of the two signals in the balanced signal pair.
Which means, of course, that if the two outputs are used simultaneously (perhaps to connect a powered sub to the RCA connector in addition to the main power amp being connected to the XLR connector), that a possibility arises for adverse sonic effects on the balanced signal path, and on the unbalanced signal path as well. Which may or may not be significant depending on the impedances that are involved, as well as the cable lengths and cable types.
Regards,
-- Al
Which means, of course, that if the two outputs are used simultaneously (perhaps to connect a powered sub to the RCA connector in addition to the main power amp being connected to the XLR connector), that a possibility arises for adverse sonic effects on the balanced signal path, and on the unbalanced signal path as well. Which may or may not be significant depending on the impedances that are involved, as well as the cable lengths and cable types.
Regards,
-- Al