Thanks for the reply!
I was just about to post that it took some doing, but I figured out that what looked like a big blank area at the top of the screen was actually the box listing the servers added. I couldn't see the list because every time JRiver showed that window, the list and the buttons were off the top of screen at my resolution.
So I did just as you describe, associated the Marantz with the added DLNA server, but it still doesn't work no matter what settings I use, DLNA/no DLNA, DLNA Extra/No DLNA Extra, Bitstream or no bitstream, etc. My setup is HDMI from an HTPC in to the Marantz. The only way I can get it to play SACD is to use the Player, but in that case I'm not using DLNA. Also using the player, it seems not to always recognize multichannel SACDs, Sometimes it works, but sometimes it's 2 channels. Foobar plays the same tracks that JRiver thinks are 2-channel just fine as 6-channel.
I'm using a Geforce GTX 1050Ti to send HDMI to the Marantz, maybe all this has something to do with that?