ADAM Audio speakers often feature both XLR and RCA connectors. Is it possible to use both at the same time, i.e. to have two different sources connected to the speaker using both connectors?

For the AX-Series, yes, that is possible. If you use both the XLR and the RCA connectors at the same time, please make sure that only one of them transmits a signal at a time. If the speaker receives signals via both connectors at the same time, the sound will be degraded (you will hear both sources simultaneously).

Please note that this does not apply to the F Series. Here the RCA jack disconnects the XLR input.

The T Series and A Series come with an input switch which allows you to choose between XLR and RCA.

S Series and SX Series models are not equipped with RCA connectors.