You are correct. Your model doesn't appear to have a single LFE connection but a combines LR connection.
The owners manual shows a split Y cable. That's what the owners manual shows so that's your ticket.
The PSw12 does use an LFE, but not the 10. Good thing those are pretty inexpensive type of cables.
Back in the day when I had a sub like that I used a Y connector (just a little stubby thing) and it connected
to a single RCA coax cable that ran to the AVR. It works.
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