LG OLED G6 (G64LW, G66LS) vs TCL A400 PRO

The LG G6 is currently one of the brightest OLEDs on the market. Its peak brightness reaches nearly 2500 nits and, best of all, this translates directly to real movie scenes. The TV flawlessly extracts details in the bright areas of the image. And this is regardless of whether we are talking about very small points in the form of stars in the sky or slightly larger elements on the screen. Naturally, with full-screen, uniformly white scenes, the brightness of the G6 drops due to the panel protection system (ABL). However, in real, varied movie shots, this value still hovers around an impressive 2000 nits, which can be considered a remarkable result. The coverage of the color palette also deserves praise. The new 2nd generation Tandem OLED panel has brought about only a cosmetic change, but still an improvement. The coverage of the DCI-P3 color space reaches nearly 99.5%, while the ultra-wide BT.2020 is around 84%. These are very good results, although it's important to remember one thing: at extremely high brightness levels, the volume of colors will be lower than in QD-OLED panels from Samsung Display due to the use of white sub-pixels (WOLED). However, in everyday content and most films, capturing this difference will be very difficult.

The TCL A400 Pro is a moderately bright TV. Its peak brightness reaches around 600 nits. That level already allows for a real HDR effect and in many films it does deliver a noticeably more appealing picture than in SDR. However, it’s not a level that dazzles by brightness alone. The A400 Pro is not one of those TVs that bombard the viewer with a powerful flash in every dramatic scene. The biggest limitation is visible with small bright elements on a dark background. Because of fairly aggressive zone control, the TV can significantly reduce their brightness, in extreme cases down to around 100 nits. That means small lights, sparks, stars or single highlights can be much less visible than they should be. It should be added, though, that this isn’t done without reason. The A400 Pro does this to keep black levels as deep as possible and to limit the halo effect around bright objects. It’s a deliberate compromise: the TV more often opts for deeper blacks rather than maximising point highlights. On the one hand this is understandable, especially given a limited number of dimming zones, but on the other you should be aware that the HDR effect won’t always be as strong as the peak brightness alone might suggest.

On the plus side, the colours are a strength. The PFS LED filter used here, marketed by the manufacturer as QLED, delivers suitably saturated colours. Our measurements showed about 94% coverage of the DCI-P3 gamut and around 74% of BT.2020, which is a solid result for this class.

We tested the LG G6 in the best factory mode for colour fidelity, which is FILMMAKER MODE. In the case of our test unit, this mode was reasonably well tuned straight out of the box. In SDR content, the only issue we noticed was the white balance, which leaned towards warmer tones. This made the image occasionally appear slightly yellowish, but overall, it wasn't a significant problem. The G6 performed a bit worse in HDR content. There, the white balance showed too much blue component. This caused the image to veer towards cooler shades, resulting in quite noticeable errors. As can be seen on our ColorChecker chart, the colours shifted towards these cooler registers. Nevertheless, considering the factory settings, the television presented a perfectly decent level. However, we know that OLED screens – particularly those from LG – respond exceptionally well to professional calibration, so we immediately proceeded to do just that.

As usual, we carried out colour measurements in the best‑tuned picture mode, Filmmaker Mode, the one intended to be closest to the creators’ intentions. The A400 Pro, of course, also offers other picture modes, but in practice they show much larger colour errors and interfere more with the image character. So we won’t cover them in detail in this part of the review. How does the factory colour reproduction fare? In short: really very well. In fact, looking at our measurements, it’s excellent. Both the white balance and the luminance response were set surprisingly precisely. The errors were so small that during the measurements we genuinely rubbed our eyes in surprise. Such good factory settings don’t happen often, even in televisions running Filmmaker Mode. All the more reason to praise TCL, because the A400 Pro straight out of the box can produce an image very close to how the source material should look. The results were so good you could easily think someone had already given this unit extra attention and tried to calibrate it. Our one bit of nitpicking comes down to a single issue. In SDR material the image was slightly brighter than the reference for a dark room, because the factory gamma was set closer to 2.3 than 2.4. It’s not a large error and most viewers probably won’t even notice it. We should note, however, that we are talking about our specific test unit. There can always be some variation in factory colour between individual units, production batches or screen sizes. We do not assume every A400 Pro will look identical straight out of the box.

After completing a professional calibration, we gained complete control over the panel, and we managed to align all parameters to nearly zero. We were able to tune the white balance perfectly, which removed the factory's cool and warm tints from the screen. The effects are visibly clear in the ColorChecker test – the average colour reproduction errors dropped below the critical value of 1-2. And what does this mean? PERFECT colours, without any distortion! However, as a reviewer’s duty, we must point out how the LG G6 arbitrarily manipulates brightness, which is due to the EOTF curve's behavior. When we look at the standard synthetic graph, it might seem that the line is quite straight. However, the situation changes when we turn on the measurement filter, which shows how the television interprets brightness in actual, moving film scenes (EOTF in MOVIES). Then, it is clear as day that some of the smallest fragments on the screen are slightly overly brightened by the algorithm. Of course, for the average viewer, such a deviation will practically go unnoticed, but in the test of such an expensive screen, it’s worth noting – especially since we are talking about a model that has huge aspirations for the title of the best television of the year.

Despite the outstanding factory tuning, we couldn't resist checking how the TCL A400 Pro would respond to professional calibration. With such a strong starting point, we were especially curious whether we could squeeze even more from this TV. And here we have to boast: we managed to bring our sample to absurdly low colour errors. Results below 1 are something you don't see every day, even on very good TVs. Such outcomes are more often associated with professional reference monitors than with a lifestyle TV for the living room. In terms of white balance and colour reproduction, the A400 Pro after calibration simply excelled. The only thing we can pick on after closer analysis concerns the brightness response. The TV can vary the luminance level depending on the content being displayed, and quite often the picture is a little darker than it should be according to the reference. This most likely stems from the way the Mini-LED backlight and the local dimming algorithms work in this model. That said, it doesn't ruin the overall impression, because in terms of colour precision the A400 Pro after calibration reached a level that was genuinely hard to expect.

No matter what one might say about the G6's issues with near-black signal, it must be fairly acknowledged that it handles heavily compressed material and lower resolution content extremely well. All unwanted, ugly tonal transitions are effectively reduced here by the "Smooth Gradation" feature. At the "Low" setting, the algorithm works flawlessly – effectively masking the artifacts resulting from strong compression without destroying the sharpness and details in the frame. Higher levels of this feature do further smooth the image, but they start to blur the real texture elements of the objects, so we recommend keeping this slider at a low level. As for the actual upscaling to 4K, the processor does an excellent job – edge sharpness and detail reconstruction are at the highest level, and in this respect, the G6 is on par with the global leaders.

Digital image processing is unfortunately one of the weaker points of the TCL A400 Pro. That does not mean the TV performs badly, but it’s hard to call it anything clearly above standard. The upscaling itself is acceptable: edges are fairly well smoothed, the picture does not look overly sharp or “pixelated”, and lower-quality material can be watched without major discomfort. At the same time the overall image has a slightly soft character and you don’t see the kind of precision that the best image processors in more expensive TVs can offer.

Handling of tonal transitions caused by heavy compression is much worse. TCL equipped the A400 Pro with a “Gradual Smoothing” feature that in theory should reduce visible colour banding and artefacts in lower-quality material. In practice, however, its effectiveness is very limited. It does not improve tonal transitions in any noticeable way, and at higher settings it can further smooth image detail, giving it an artificial, slightly blurred character. For that reason we think it’s best to leave this feature off. The A400 Pro copes decently with basic image scaling, but if you often watch heavily compressed material with visible posterisation, this model will not be one of the best choices.

The LG G6 is an OLED television, so in the category of motion fluidity, it traditionally deserves the highest marks. The TV supports very high refresh rates of up to 165 Hz in 4K resolution, but most importantly – there are absolutely no signs of blurring on the screen. The response time of the matrix is virtually instant, ensuring that dynamic images remain perfectly sharp.

The TCL A400 Pro is equipped with a 144 Hz panel, but in practice we're most interested in how it performs at 120 Hz. That's the refresh rate most consoles, as well as many sports broadcasts and high-motion sources, are limited to today. In that range the TV performs quite well. Motion clarity is really good, especially after properly configuring the motion smoothing. The 'Motion Clarity' function improves smoothness. Its settings include two sliders that let you tailor the motion smoothing to your preferences, separately for low-frame-rate and high-frame-rate content. This allows you to achieve either a more cinematic look or a noticeably smoother image. If you don't want to fiddle with manual configuration, you can use built-in presets such as Low, Medium, High, Cinema or Nature.

The LG G6 is a true beast for gamers and one of the best-equipped TVs on the market in this regard. The manufacturer didn't compromise and equipped this model with four full HDMI 2.1 ports with a maximum bandwidth of 48 Gbps. This means that no matter which port you plug in your PlayStation 5, Xbox Series X, or powerful PC, you'll get the absolute maximum performance out of them.

The TV supports a full suite of gaming technologies: from VRR (Variable Refresh Rate), to AMD FreeSync Premium Pro, and Nvidia G-Sync Compatible. Let's add to that a remarkably low, almost imperceptible input lag and an excellently functioning game panel (Game Optimizer), which allows you to constantly monitor signal parameters. Gaming on this screen, with the perfect black of OLED and powerful refresh rates, is pure pleasure.

In terms of gaming features the TCL A400 Pro performs brilliantly. The TV has practically everything you’d expect from a gaming TV today: support for 4K at high refresh rates, VRR, ALLM, correct implementation of HDR formats in games, including Dolby Vision, and HGiG. That means it works well with both next‑gen consoles and PCs. Another plus is the inclusion of a Game Bar, a dedicated panel with the most important settings for gamers. From it you can quickly check basic information about the signal, refresh rate or active features, and customise the appearance and behaviour of some settings to your preferences. It’s a solution that may not change picture quality by itself, but it greatly improves the convenience of using the TV while gaming. The only thing to criticise is the number of full HDMI 2.1 ports. The A400 Pro has only two such ports out of four, and one of them also serves as eARC. In practice this means that if you want to connect two next‑gen consoles and a soundbar you may run into some limitations. In that scenario you’ll need to either swap devices or use extra equipment, such as an AV receiver or a soundbar with HDMI inputs. Even so, it’s hard not to rate the A400 Pro very highly as a gaming TV. The gaming feature set here is genuinely powerful.