You need to read your manual and/or consult ML about this. If there is no balanced/unbalanced switch on the amp, it is very likely you cannot do what you propose as the two input will interfere.
Even if there is a switch, it may only be for the purpose of changing the input impedance appropriately and, therefore, preclude connecting both sources simultaneously.
Kal
Even if there is a switch, it may only be for the purpose of changing the input impedance appropriately and, therefore, preclude connecting both sources simultaneously.
Kal