I wouldn't normally contradict Awesome Donkey as he is very knowledgeable and is very generous with answering questions. However, I'm pretty sure this advice is incorrect. That setting applies to JRiver *clients* connected to JRiver servers.
In this case JRiver is pushing DLNA audio to a DLNA renderer. Therefore, the correct setting to modify is:
Tools > Options> Media Network > Add or Configure DLNA servers
From there, you can adjust the Generic DLNA profile to send PCM audio instead of MP3 audio.
Or you can add the "Audiophile" DLNA profile and then associate that profile with your DLNA renderer. The associate part is done after you set it up. You associate it by right clicking on the DLNA renderer name (in the left hand navigation area) and choosing the option to associate a DLNA profile.
Good luck.
Brian.