You may need to experiment with your upscaling settings here. Say you're watching an SD channel on a 4K UHD TV, then you have 2 levels of upscaling, and many people report success by the V6 outputting at 1080 and the TV doing the rest - but SD at 2160 is going to have poor results sooner or later,...
VM's HD pictures should be at least a match for other platforms, so something's not right here. Have you tried another HDMI cable or slot on your TV?
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