TCL A400 PRO vs Samsung S90H (QD-OLED)

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.

The Samsung S90H is a genuinely bright TV for the mid-range OLED segment. In synthetic tests its peak brightness reached around 1650 nits. That’s an impressive result in this class, roughly 50% higher than what we have seen from previous models in this price bracket. Most importantly, these tests translate directly to real video material. In four out of five film clips we tested, the S90H’s brightness ranged between 1300 and 1500 nits. That headroom allows it to reproduce most HDR films with very high dynamic range and without obvious compromises, especially in material mastered to 1000–1500 nits. In practice light effects, reflections and explosions have the appropriate punch, and the picture does not appear dimmed. Of course, on full-screen very bright scenes the result is naturally lower and drops to around 900 nits. This is a direct result of the OLED panel’s protection systems working to prevent overload. Even in this scenario there is little to complain about. Those 900 nits across the whole screen is still a very high level, ensuring excellent dynamic range in HDR content.

Colour has always been a major strength of QD-OLED TVs, and the S90H is no exception. The DCI-P3 colour space we measured reached a full 100% (actually 99.9%), while coverage of the much wider BT.2020 gamut hit about 89%. That’s an excellent result, enabling very saturated and vivid colours in HDR content. It’s worth emphasising that QD-OLED’s advantage over WOLED panels is not limited to palette coverage alone. In practice it’s mainly visible in the higher brightness of saturated colours, that is in a greater colour volume. As a result, intense reds, greens and blues in HDR look more vibrant and more striking.

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.

The next stage of the test was to check how the S90H handles colour reproduction without any calibration. As always, we carried out the measurements in Filmmaker Mode, the best factory picture preset. And here Samsung really deserves praise. The factory tuning is at a very high level, and a few years ago this was not one of its strong points. The average colour error (Delta E) remained around 3, which is below the level at which most people can notice any inaccuracies. Only in the brightest shades of grey did the values slightly approach 4, but even then it's hard to regard this as a real problem while watching. For out-of-the-box settings, the result is simply excellent.

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.

All right, but you know we wouldn't be ourselves if we didn't also check how far we could push the S90H after professional calibration. And there was no big surprise. Since the factory settings were already very good, there wasn't much room for improvement. Even so, we managed to refine the picture to near perfection. After calibration the mean colour reproduction errors fell below the threshold of perception, with Delta E values under 2 for both SDR and HDR material. We also improved the brightness response, so the image more faithfully reflects the creators' intent and maintains appropriate tonality across the whole luminance range. After professional calibration the S90H therefore becomes a display very close to reference.

Will the difference be spectacular for everyone? Not necessarily. The factory settings already deliver a very high level, so in everyday viewing some people may not notice a dramatic jump. Much also depends on the individual unit. Our sample was very well tuned straight out of the box, but that doesn't mean every S90H will perform at the same level. Even identical models can differ from each other in terms of factory calibration. That's exactly why professional calibration makes sense: it allows a specific unit to be brought to the highest possible accuracy, rather than relying on a bit of luck when buying.

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.

In this respect Samsung has changed practically nothing compared with last year’s model, which is actually quite good news. The feature responsible for smoothing tonal transitions still very effectively limits the posterisation effect. However, you should remember that it works rather aggressively, because besides the artefacts themselves it can also remove film grain and slightly soften fine image detail. As always, this is therefore a matter of compromise and personal preference. If you want the most faithful reproduction of the source material possible, we recommend leaving this function turned off.

There is also little to be said about upscaling in terms of revolution. The S90H uses the same proprietary NQ4 Gen3 image processor as its predecessor, so scaling quality has remained practically unchanged. The TV handles lower-resolution material well, effectively improving its sharpness. However, the overscan problem has still not been solved. With some older material, especially archival recordings, it may happen that a portion of the image at the edges is cropped. It’s a minor flaw, but a shame Samsung has left this issue unchanged for another year running.

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.

In terms of motion handling the S90H delivers a very high level. A new feature here is a panel with a refresh rate of up to 165 Hz, although in practice that will mainly benefit PC gamers. Films, series and sports broadcasts do not use such high refresh rates, so when watching them the difference compared with the standard 120 Hz will not be noticeable. That said, thanks to the OLED panel's lightning-fast response time motion is very clean and the picture does not suffer from the motion blur typical of many LCDs. Samsung has equipped the television with extensive motion-smoothness settings. You get two sliders: judder reduction and blur reduction, which let you easily tailor the picture's character to your own preferences. You can easily achieve a very smooth image when watching sport, but you can just as well preserve a more cinematic feel at the typical 24 frames per second. It all depends on which effect you prefer.

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.

From the outset the Samsung S90H feels like a TV designed with gamers in mind, and it's easy to see why. The manufacturer has equipped it with almost everything you could expect from a modern gaming screen. You get as many as four full-bandwidth HDMI 2.1 ports, support for ALLM and VRR, and very high refresh rates. There's also a clear Game Bar that lets you instantly check key picture parameters or change settings without leaving the game. Another very welcome improvement is the HGiG behaviour. Last year it could cause quite a few problems, but on the S90H it works exactly as it should.

Samsung's ace up its sleeve remains its proprietary Game Motion Plus mode. The feature works similarly to the motion smoothing used for films: it improves animation smoothness in games while keeping input lag at a very reasonable level. For titles running at 30 or 60 fps, with the right settings input lag did not exceed 40 ms in our tests. That's a very good result, especially since with many manufacturers enabling similar features results in delays several times higher. Game Motion Plus does not, of course, replace Dolby Vision Gaming, as it's a completely different type of feature, but overall it's a gaming addition that many players may find more noticeable. Smoother motion in 30/60 fps games often makes a bigger difference than HDR itself (which, incidentally, is often poorly implemented in games).