As Mofi indicated, usually both outputs will be active simultaneously, or they can be made so via menus.
However, in a lot of designs the balanced and unbalanced outputs are driven by the same output stage, and in a lot of those cases the RCA output is internally connected directly to the non-inverted signal pin on the XLR connector. In those cases using the RCA and XLR outputs simultaneously may result in at least a slight degree of compromise sonically, depending on impedances, cable lengths, and a number of other variables.
Ideally you would want the design to provide separate and independent output stages for the RCA and XLR outputs. The manual might indicate whether or not that is provided, or else an email to the manufacturer would hopefully provide an answer.
Regards,
-- Al
However, in a lot of designs the balanced and unbalanced outputs are driven by the same output stage, and in a lot of those cases the RCA output is internally connected directly to the non-inverted signal pin on the XLR connector. In those cases using the RCA and XLR outputs simultaneously may result in at least a slight degree of compromise sonically, depending on impedances, cable lengths, and a number of other variables.
Ideally you would want the design to provide separate and independent output stages for the RCA and XLR outputs. The manual might indicate whether or not that is provided, or else an email to the manufacturer would hopefully provide an answer.
Regards,
-- Al