Drubin...An Optical-to-Coax converter can be found at www.partsexpress.com item 180-961.
However, reading the DEQ2496 manual, I see that the digital output which is on an XLR connector can be switched between the professional format, AES/EBU, and the consumer format S/PDIF. You select the format using the I/O menu of the DEQ2496. It says that you can use an adapter to go from XLR to RCA for the digital output. Nothing is said about how this adapter is wired. I would get a standard balanced XLR to unbalanced RCA and give it a try.
However, reading the DEQ2496 manual, I see that the digital output which is on an XLR connector can be switched between the professional format, AES/EBU, and the consumer format S/PDIF. You select the format using the I/O menu of the DEQ2496. It says that you can use an adapter to go from XLR to RCA for the digital output. Nothing is said about how this adapter is wired. I would get a standard balanced XLR to unbalanced RCA and give it a try.