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 what’s best – this has a direct impact on real film scenes. The television flawlessly extracts details in the bright areas of the image. And this is regardless of whether we are talking about very small points like stars in the sky or slightly larger elements on the screen. Naturally, with full-screen, uniformly white scenes, the brightness of the G6 decreases due to the panel protection system (ABL). However, in real, varied cinematic shots, this value still hovers around 2000 nits, which can be considered an outstanding result. The coverage of the colour palette also deserves praise. The new second-generation Tandem OLED panel only brought a cosmetic change but still an improvement. The coverage of the DCI-P3 palette reaches nearly 99.5%, whereas for the ultra-wide BT.2020, it is around 84%. These are very good results, although it’s worth remembering one thing: at extremely high brightness levels, the colour volume will be lower than in Samsung Display’s QD-OLED panels due to the use of a white sub-pixel (WOLED). However, in everyday content and most films, catching 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 produce a noticeably more attractive picture than in SDR. However, it is not a level that overwhelms with sheer brightness. The A400 Pro therefore isn’t one of those TVs that ‘attack’ the viewer with a powerful flash in every eye-catching scene. The biggest limitation is seen with small bright elements on a dark background. Because of fairly aggressive local dimming control, the TV can significantly reduce their brightness, in extreme cases even to around 100 nits. This means that small lights, sparks, stars or individual highlights can be much less visible than they should be. It’s worth adding, however, that this isn’t without reason. The A400 Pro does this to maintain as deep a black level as possible and to limit the halo effect around bright objects. So it’s an intentional compromise: the TV more often opts for deeper blacks rather than maximally bright, point-like highlights. On one hand this can be understood, especially given the 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, allows for suitably saturated colours. Coverage of the DCI-P3 gamut measured around 94%, and BT.2020 around 74%, which is a solid result for this class.

We tested the LG G6 in the best factory mode in terms of colour fidelity, namely FILMMAKER MODE. In the case of our test unit, this mode was quite well tuned straight out of the box. In SDR content, the only issue we could point out was the white balance, which tended to drift towards warmer tones. Consequently, the image could occasionally appear slightly yellowed; however, overall, this was not an bothersome problem. The G6 performed a bit worse with HDR content. There, we noted too much blue component in the white balance, which caused the image to take on cooler hues, resulting in fairly noticeable errors. As can be seen in our ColorChecker chart, the colours indeed drifted towards these cooler registers. Nevertheless, considering the factory settings, the television displayed a perfectly decent level. We do know, however, that OLED screens – particularly those from LG – respond excellently to professional calibration, which is why we immediately went ahead with it.

As standard, we performed colour measurements in the best‑tuned Filmmaker Mode, the mode that is designed to be closest to the creators' intentions. The A400 Pro of course also offers other picture modes, but in practice these come with considerably larger colour errors and interfere more with the character of the image. Therefore we will not deal with them in detail in this part of the test. So how does the out‑of‑the‑box colour reproduction fare? In short: really very good. Actually, looking at our measurement results, downright excellent. Both the white balance and the luminance response were set surprisingly precisely. The errors were so small that during measurements we genuinely rubbed our eyes in amazement. Such good factory settings do not happen often, even in TVs operating in Filmmaker Mode. All the more credit is due to TCL, because the A400 Pro right out of the box can deliver an image very close to how the source material should look. The results were so good that one could easily think someone had already given this unit extra attention and tried to calibrate it.

Our nitpicking really comes down to just one thing. In SDR content the image was slightly brighter than the dark‑room reference intends, because the factory gamma was set closer to 2.3 than to 2.4. This is not a large error and most viewers will probably not even notice it.

It should, however, be noted that we are talking about our specific test sample. With factory colours there can always be some variation between units, production batches or screen sizes. We do not assume, therefore, that every A400 Pro will look identical straight out of the box.

After professional calibration, we gained complete control over the panel, and we managed to align all parameters to nearly zero. We successfully calibrated the white balance perfectly, which eliminated the factory cool and warm tints from the screen. The effects are clear as day in the ColorChecker test – the average colour reproduction errors dropped below the critical value of 1-2. And what does that mean? PERFECT colours, without any distortion! However, as reviewers, we must point out here how the LG G6 arbitrarily manipulates brightness, for which the EOTF curve is responsible. When looking at the standard synthetic chart, 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 real, moving film scenes (EOTF in MOVIES). Then it becomes evident that some of the tiniest parts on the screen are slightly over-brightened by the algorithm. Of course, for the average viewer, such a deviation will be practically unnoticeable, but in the test of such an expensive screen, it is worth noting – especially since we are talking about a model that has huge aspirations to be named the best television of the year.

Despite its superb factory calibration, we couldn't resist checking how the TCL A400 Pro would respond to professional calibration. Since the starting point was so good, we were all the more curious whether there was anything more to be had from the TV. And here we must boast: we managed to reduce our unit's colour errors to absurdly low levels. Measurements below a value of 1 are not something you see every day, even in very good TVs. Such results are more commonly 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 therefore simply performed exceptionally well after calibration. The only gripe we have after closer analysis relates to the luminance behaviour. The TV adjusts luminance depending on the content being displayed and quite often the picture is slightly darker than the reference calls for. This is most likely due to the way the Mini-LED backlight and local dimming algorithms operate in this model. However, this does not spoil the overall impression, because in terms of colour accuracy alone the calibrated A400 Pro showed a level that was really hard to expect.

Whatever one may say about the G6’s problems with near-black signal, it must be fairly acknowledged that it handles heavily compressed material and lower resolution content exceptionally well. All unwanted, unsightly tonal transitions are effectively reduced here by the "Smooth Gradation" feature. At the "Low" setting, the algorithm works flawlessly – effectively masking the artefacts resulting from strong compression without destroying the sharpness and details in the frame. Higher levels of this function do indeed smooth the image further, but they start to blur the real elements of object texture, which is why we recommend keeping this slider at a low setting. As for the upscaling to 4K, the processor does an excellent job – edge sharpness and detail reconstruction are at the highest level, and in this regard, the G6 does not fall behind the world leaders at all.

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 is hard to call it anything clearly above average. The upscaling itself is adequate: edges are smoothed fairly well, the picture does not look overly sharp or "pixelated", and lower-quality content can be watched without much discomfort. At the same time, the overall image is slightly soft and lacks the precision offered by the best image processors in more expensive TVs.

Much worse, however, is how it handles tonal transitions caused by strong signal compression. TCL has equipped the A400 Pro with a "Gradual Smoothing" feature that, in theory, should limit visible colour banding and artifacts in lower-quality material. In practice, though, its effectiveness is very limited. It does not improve tonal transitions in any noticeable way, and at higher settings it can also smooth out image details, giving the picture an artificial, slightly blurred character. For that reason, we think it is best to leave this feature off. The A400 Pro copes decently with basic image scaling, but if you often watch heavily compressed content with noticeable posterisation, this model will not be among the best choices.

LG G6 is an OLED television, so in the category of motion fluidity, it traditionally deserves the highest marks. The television supports very high refresh rates reaching up to 165 Hz in 4K resolution, but most importantly – on the screen, you will not notice any signs of blurring. The response time of the panel is almost instantaneous, ensuring that dynamic images remain perfectly sharp.

The TCL A400 Pro is equipped with a 144 Hz panel, but in practice we are most interested in its behaviour at 120 Hz. That is the frequency most consoles are limited to today, as well as many sports broadcasts and high-frame-rate content. At that rate the TV performs quite well. The sharpness of moving objects is really good, especially after properly configuring the motion smoothing. The "Motion Clarity" function is responsible for improving smoothness. Its settings include two sliders that let you tailor how the motion smoothing operates to your preferences, separately for lower and higher frame-rate material. This makes it possible to achieve both a more cinematic look and a noticeably smoother picture. Those who do not want to fiddle with manual configuration can use presets such as low, medium, high, cinema or nature.

The LG G6 is a true monster for gamers and one of the best-equipped televisions on the market in this regard. The manufacturer has not skimped on features, equipping this model with as many as 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 will get the absolute maximum performance from them.

The television supports a full set of gaming technologies: from VRR (Variable Refresh Rate) to AMD FreeSync Premium Pro, and even Nvidia G-Sync Compatible. On top of that, it offers remarkably low, nearly imperceptible input lag and an exceptionally well-functioning Game Optimizer panel, which allows you to monitor signal parameters in real time. Gaming on this screen, with the perfect black of OLED and impressive refresh rates, is pure pleasure.

In terms of features for gamers the TCL A400 Pro performs brilliantly. The TV has practically everything you can 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-generation consoles and a PC. Another plus is the presence of the Game Bar, a special 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 also adjust the appearance and behaviour of some settings to suit your preferences. This solution may not change picture quality by itself, but it greatly improves the convenience of using the TV while gaming.

The only thing to complain about is the number of full HDMI 2.1 ports. The A400 Pro has only two such connectors out of the four available, and one of them also serves as eARC. In practice this means that if someone wants to connect two next-generation consoles and a soundbar, they may run into some limitations. In that scenario you will have to either swap devices or use additional equipment, such as an AV receiver or a soundbar with HDMI inputs. Even so, it is hard not to rate the A400 Pro very highly as a TV for gamers. The gaming feature set here is truly powerful.