Q: Can I connect AES digital signal to S/PDIF input, vice versa?
A: As far as the data goes, there should be no problem connecting these two digital formats. Electronically, in most cases, interconnecting them will also work fine. However, in some cases, the different impedances and signal levels may cause problems, including damage to the devices (though this is fairly rare these days).
If you want to be sure, converter boxes are available to change one format into the other. Or, make your own custom converter cable. Simply wire an XLR connector to one end, and an RCA connector to the other, with this pin out: