Plasma owners rarely accept any LCD and even OLED as same or better. You have a Rolls Royce HDTV so you'll be very hard to please.
Cable content can also be 1080i or lower so scaling that to 4K may do nothing more than amplify the visual defects in the source.
Again, OLED should have a fair shot at war with the plasma but due to how plasma works, you may not like OLED. You are doing the right thing of testing and returning products that don't meet your requirements.
Be sure to call in on each new model to be sure the firmware is current as well to chat about upscale failures.
Don't know if this has been asked previously, my apologies if it has. My question has to do with up-scaling of standard cable content to 4K. I purchased a LG OLED55e7p last week, set it up on Saturday, and decided to return it on Sunday. Let me first state that most of the content I view is on Verizon cable. My set up prior to and now again that I am returning the LG, is a 2014 Samsung F8500 51" Plasma, and I route all content through a OPPO 103D blu ray player with Darbee presence at a level of 13. The picture on the Samsung as set up is gorgeous, be it cable or blu ray.
Setting up the LG, I used half a dozen calibration profiles garnered from the internet, in addition to the out of box profile. The LG rendered content from blu ray and even DVD discs beautifully, and I could not be more pleased with that content. Cable on the other hand, felt like I took a giant leap backward to 720p versus the view on my Samsung / Oppo setup. I have since read from several review sources online, that what I am experiencing is in fact the case, that HD or SD cable content will never look as good on a 4K panel as it will on a 1080p panel.
Bottom line, my question: is it worth looking at the Sony OLED, as Sony has a reputation for excellence in electronic processing, and their up-scaling may be superior to LG. Or should I simply stay with my Samsung / Oppo setup for now? Thanks to anyone who might have similar experiences or technical knowledge / thoughts.

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