XPA-2 - issue - speaker - advice needed !

Morning - I have a relatively simple setup  -  Yamaha R-S700 two-channel receiver; Emotiva XPA-2; Polk Audio RTI-A9 tower speakers; and Bose bookshelf speakers.

Before I installed the Emotiva, I was running four speakers through the Yamaha receiver.  When I installed the Emotiva, I removed two "jumper pins" from the coupler port and installed the Emotiva jacks into the "Pre Out" port.  Now, when I power the system up, I only get sound from the Polk speakers hooked up to the Emotiva.  If I remove the Emotiva jacks from the Yamaha receiver and replace the jumper pins, I get sound from all four speakers again.  What am I doing wrong?  Thank you much.

"mono male RCA to dual male RCA cables"

Actually dual male to single female will work much easier. The 2 males into the Yamaha and the single female for the cable going to the Emotiva. Like this,


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This original post and quick resolution by a couple of supportive members makes me believe there is hope for this forum after all.

My thanks to mzkmxcv and tls49 as well.