Balanced DAC with mono output?

Hello:

I'm looking for S/PDIF DACs (current production or used) with balanced outputs and a mono output mode.

Usage: Sonos → DAC → single active monitor. The Sonos unfortunately doesn't have a mono mode. I'd rather do mono in the DAC than use a passive summing box.

So far, after much research, I've found these:

• Presonus Monitor Station 2
• Audient iD14 (software-configurable button)
• TC Electronic BMC-2
• Lavry DA10 (but not DA11)
• Mytek Stereo192

Any others? Most DACs seem not to have a mono output mode.