I just bought the soundbar 700 system and have some trouble connecting it to my Epson projector and fire tv. Since the projector only has aux port I’m currently using a HDMI audio extractor to send audio to soundbar via toslink but the signal is not very stable. I’m considering buying an av receiver like Onkyo 686 which has both HDMI ARC and HDMI ports. Is that receiver compatible with soundbar 700? Thanks.
The HDMI ARC on the amp you're looking at is to return audio to the amp, not to send audio from the amp to something else. It may be best to see if it has on optical out for a second zone, but depending on the amp you could lose quality.
Realistically Soundbars are not designed to receive signals in this way, but there can be ways around it.