The Pioneer has L/R stereo output, so I would just connect the output here directly to the Adam A8X speakers.
How many sources do you have?
If you have just one source like BDR, then it's fine.
If you have more than one source, then you will have to use the ZONE 2 output. But then I think you can only connect analog inputs and cannot use HDMI switching to Zone 2. I think you can only do Analog for everything on Zone 2 - component video, RCA audio.