Converting Coax to AES?

Can I just use a RCA to XLR adapter?

I realize it may not be optimal, but this is for my DirecTV box, not more critical sources.
no. The voltage is different, and the units will not communicate properly.
I have never read of anyone doing so successfully.
Also the impedance difference will mess up the waveform.

Here is one solution, for $98, although I suspect that with a little looking you'll be able to find something less expensive (this one can handle two signals, which you don't need):

-- Al
Canare makes several models of impedance transformers that can adapt a coax cable to an AES input. I used to use one to connect a computer coax digital audio output to an AES input on my DAC because the DAC RCA coax input was being used to connect a cd player. The one I Used has a BNC type connection on the back so I used an RCA/BNC adapter to connect the coax cable. The model I used cost a little over 20 dollars and worked great for digital audio. It was recommened to me by the maker of my Grace M902 DAC. I found a Canare model BJC-XJ-TRB Impedance Transformer XLR Jack to BNC Jack when I did a Google search priced for $22.99.
Thanks guys--I ordered the Canare first. If that doesn't work, than the Hosa box will replace it.