Not sure if this amp was ever used, its in great condition - I don't have a strong enough line level connection to test it - However everytime I plug my phone using a RCA connection the light under the corresponding input on the front panel lights up and reacts to volume changes. I have 4 Ohm speakers in my test set up so not sure if that is causing a problem 

Link to Manual: https://www.crownaudio.com/en-US/product_documents/140497-2_08-13_135ma-160ma_operation-pdf-2582451f-4c46-4ad0-9f3a-836e9c22561d