Neither of those TVs you're looking at have local dimming so you won't get black levels that are close to your plasma.
good black levels to get closest to plasma quality on an LED TV
The only thing remotely close to the blacks of you plasma.
I’m calling shenanigans. That’s not even remotely true. Particularly for a THX certified calibrator to make such a claim is shameful. The cheapest LEDs on the market today will hit the black levels of most plasmas.
With the exception of Kuros and some of the Panasonics most plasmas never had better black levels than LEDs, even without local dimming. They had better black levels than early LCD displays and anything IPS, sure, but early LEDs were said to give the best of both worlds; bright AND good blacks.
Go look at Rtings Samsung reviews and check the oldest ones listed. There’s both LED and plasma models. The LEDs generally measured lower black levels. Their black levels would rise a bit with increased brightness, but plasmas couldn’t get that bright anyway. Plasmas had pixel level control, better uniformity and better motion, but to say as a rule that they had better black levels just isn’t true.
Don’t spread misinformation as a knee jerk response, making someone think they need x feature just to match their current experience. Something like a TCL 4 series will match a plasma for a fraction of any set mentioned here if all the poster wants is to upgrade to 4k. It’s silly to guide someone to spend 4x that unless we know it actually fits their needs and preferences, particularly when they specifically asked that we help that not blow their money
So FALD is a new requirement.
The answer to that is NO, or more accurately, it depends. If all you want to do is match your plasma for SDR content the Q70T/A is arguably the best choice, precisely because it lacks local dimming. In the 100-200 nit range it’s going to display its calibrated gamma curve with its native contrast and be extremely plasma like.
It’s HDR where local dimming matters most. As the backlight strength increases the black levels will increase. Dimming the backlight in dark areas helps improve black levels. BUT, there are inherent trade-offs. Blooming around bright objects on dark backgrounds, dimming of bright objects on dark backgrounds, and/or overly darkening resulting in black crush/loss of shadow detail are all common side effects. Which side effects and their magnitude varies based on model, manufacturers preference, and the algorithms that control it all.
The Q70T/A doesn’t do any of that, so it won’t have those side effects. It may still have some issues inherent in backlit tvs, but it won’t be at the mercy of a local dimming algorithm. The tradeoff, of course, is decreased contrast, particularly in HDR content.
For my personal tastes I think a lot of high end modern tvs make SDR cable and streaming look weird. They exaggerate darkness in a way that is reminiscent of my old plasma in its highly inaccurate custom mode, where black ‘enhancement’ stripped too much detail from anyone with dark hair or wearing a dark suit. I’d rather watch with local dimming off and have what I consider a lower, but more natural, contrast.
HDR content is coded completely differently and is meant to have much greater contrast. Bright highlights won’t pop if they’re dim or black levels are bad, and it’s tough to keep good black levels with 500-1000+ highlights. Local dimming increases the pop, but then we’re back at the side effects I mentioned previously.
No local dimming, aggressive local dimming, and mild local dimming are all different but all are valid. They each have pros and cons. Which you choose is a matter of preference. What one person loves another will hate and vice versa. I wish I could tell you there’s an easy way to identify your preference, but with little opportunity to see tvs these days outside of bright showrooms playing pristine demo content in vivid mode it’s a matter of researching, taking your best guess, then seeing what’s it’s like to live with a tv in your home for a bit.
What we really need to know to even begin to recommend anything are some details about your viewing habits and environment. What do you watch most content wise and is HDR of interest to you? Are you in a bright environment or is it light controlled?
Sorry to be so long winded, but with what we know so far I’m not sure if you need a $1,000 $3,000 or $8,000 tv and I’d like to try to help you avoid some of the upgrade woes I’ve experienced in my journey.