I am an under achiever when it comes to all the fine details of the technical aspects of HDMI and 4K and a lot of other things for that matter. I have an 861v4 along with the HD621.

I viewed the Sony 65" 4K today at the Sony store and was blown away. I almost purchased it but then I remembered reading this excellent thread.

I returned to glean these pages and my limited abilities still has me wondering.

Will it work on non 4k source material switched through the HD621.

Am I correct that if a true 4k source material is feed into the HD621 will most likely not work?

Thanks and excuse me if the answer is already in these pages and I just can't grasp it.

861v4, HD621, Ultra Classic