Kijanki, in some (and I suspect many) preamps which provide both XLR and RCA outputs the signal provided to the RCA output is the same signal that is provided to one of the two signal pins on the XLR connector. And some power amps which accept both XLR and RCA inputs receive both of those inputs through the same differential receiver stage, connecting one of the two inputs to that stage to ground when the RCA input is used.
If the preamp and the power amp are designed in that manner, when an XLR interconnection is used the differential receiver stage will be provided with twice the voltage differential at its inputs compared to when an RCA interconnection is used. The output of that stage will therefore be twice as great when an XLR interconnection is used, and hence the overall gain will be 6 db greater when an XLR interconnection is used.
Best regards,
-- Al
If the preamp and the power amp are designed in that manner, when an XLR interconnection is used the differential receiver stage will be provided with twice the voltage differential at its inputs compared to when an RCA interconnection is used. The output of that stage will therefore be twice as great when an XLR interconnection is used, and hence the overall gain will be 6 db greater when an XLR interconnection is used.
Best regards,
-- Al