If 2160 only is selected, your V6 will upscale everything to 2160 regardless of source.
If you have 1080 & 2160 selected, your V6 will upscale any SD to 1080 and output that. Any UHD is outputted at 2160.
In the second scenario, any SD/HD input to your TV will be upscale by the TV to 2160. You may need to experiment to decide whether whether V6 or your TV is best at the 1080 > 2160 bit.
I'm not near my V6 to check what my video outputs are set to, but I seem to recall having both 1080 options (including the pass through) enabled.
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