how to connect BPA300 (balanced LM3886) to input and output?

so I have tested both R+ and R- by wiring them single-ended and they are working fine.

I want to try testing them now in balanced mode. And I have connected...
  • hot pin of the XLR (pin2) to R+ PCB (this XLR cable is connected to the XLR output of DAC. Volume can be controlled in the DAC so I set the volume to -90db)
  • cold pin (pin3) to R- PCB
  • positive terminal of speaker was connected to R- PCB output
  • negative terminal of speaker was connected to R+ PCB output
This connection results in massive hum. Do I need to connect the XLR ground to the PCB ground?

Thanks!
 
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Do you have a schematic or any sort of information on this BPA300? How about asking the vendor?

To connect a differential source to a single-ended input, the best option is to use a differential receiver. But if you don't want to go that route, a cheap hack can be to connect XLR pin 2 to RCA centre and XLR pin 1 to RCA ground. Leave XLR pin 3 floating. That'll work in many cases.

Tom