OK, I have tried, meanwhile. The both cases (2x XLR-RCA cables OR XLR-RCA for Eclipse in and RCA-RCA for Eclipse out) work for me (with my gear).
So, only the question if it is better to use AES sockets for the both (in and out) or it does not matter and RCA is about the same, remains. (The equipment that I connect to Eclipse has only RCA socket )
