I know you mentioned that you have tried everything. Curious if you have tried this from the manual with the AC12/Reviver connected between the slave 3200 output and SL1600. Hope you can get it sorted like I was able to with my DSP33/DSW1500 setup.

To create a stand-alone Sooloos system
The DSP3200s can be connected directly to a Meridian Media Core 200 to make an ideal compact Sooloos system.
You can browse and control music on the system using the Sooloos application on an iPad, iPhone, or iPod Touch, or the Control:PC/Control:Mac application on a computer.
• Connect the Network socket on the Media Core 200 to one of the LAN network connections on your Router, using a CAT5 cable.
• Make sure the WAN/Internet port on the Router is connected to the rest of your network, or to your Cable/DSL Modem.
• Connect the SpeakerLink output on the Media Core 200 to the master DSP3200 SpeakerLink input, using a Meridian SpeakerLink lead.
• Connect the SpeakerLink output from the master DSP3200 to the SpeakerLink input of the slave DSP3200, using a Meridian SpeakerLink lead.
For information on configuring your Media Core 200 please refer to the Media Core 200 User Guide.

M2.0>ROON: C15/DSP6K
C2.2>ROON: ALLO DIGIONE/DSP5K+D2500x2
W2.2>ROON: C10/DSP33+D2500
R2.0>ROON R: MiniDSP SHD>SCHIIT Freya+(Forkbeard)>3eAudio A7 Mono>>>Apogee Scintilla

Projects. ROON streamer with serial RS232 volume control