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this spec sheet, it's HDMI 1.4 and ARC, so it won't passthrough 4K sources, and the ARC won't pass through uncompressed audio from your tv. Your best bet for 4k sources is to directly connect them through the TV and try to pass through the best audio you can through ARC to the receiver. It's less than ideal audio quality, but it will at least get you the 4K picture.