Redmi K90 Pro Max Review: Performance, Display and BOSE 2.1 Audio Power

In recent years, smartphone “homogenization” has become an old and recurring topic. “Hardware homogenization” has pushed smartphone brands to focus more on software, ecosystems, or actively cooperate with upstream chip manufacturers to “prioritize” their hardware requirements for performance and imaging, in order to create unique selling points. But the question is, has hardware “homogenization” really blocked all paths for hardware innovation in smartphones? Clearly, the answer is no.

The newly released REDMI K90 Pro Max is the best example that smartphone innovation “never stops.”
Balancing a large display and great in-hand feel
In terms of design, the REDMI K90 Pro Max uses the currently mainstream “aluminum alloy middle frame” structure. Its 6.9-inch OLED display with M10 luminous material brings the device width to 77.82 mm and weight to 218 g, which may feel slightly challenging for users with smaller hands. However, the large rounded corners and smooth transitions between the middle frame and the front and back panels provide a very comfortable grip, without the sharpness sometimes caused by flat frames.

In addition, the K90 Pro Max’s screen, with a peak brightness of 3500 nits, delivers truly excellent display performance: the visuals are clear and transparent, with strong anti-reflection capability, making outdoor viewing no issue. Smartphone brightness needs to be high, but also “low”: the REDMI K90 Pro Max supports an ultra-low 1-nit minimum brightness, reducing eye strain when using the device in dark environments such as airplanes or night buses. The K90 Pro Max also adopts the circular polarization 2.0 full-path DC dimming technology, a standard feature of this year’s Android flagships.

Now that we’ve covered the front, let’s look at the back of the REDMI K90 Pro Max. The K90 Pro Max does not continue the circular camera layout of the K80 Ultra but adopts this year’s popular full-width square camera module platform design. Of course, similar designs have appeared in previous REDMI devices as well—proving that design trends often come full circle.

Inside the camera module are three 50MP cameras (0.7×, 1×, 5×), corresponding to 18 mm, 23 mm, and 115 mm focal lengths. On the right side of the camera module sits the core selling point of the REDMI K90 Pro Max—the BOSE triple-speaker system jointly developed by REDMI and BOSE. As for how this three-speaker system actually performs, we will discuss that after covering the K90 Pro Max’s hardware performance.

Top-tier performance
Performance has always been REDMI’s strong suit. As REDMI’s flagship smartphone, the REDMI K90 Pro Max naturally uses the Snapdragon 8 Gen 5 Ultra mobile platform, and the unit we tested is the top configuration with 16GB + 1TB.

Regarding the Snapdragon 8 Gen 5 Ultra, most readers are already familiar with it after so many reviews. But in the K90 Pro Max, REDMI additionally includes the D2 independent display chip. Simply put, the D2 AI display chip is manufactured with a 12nm process and contains an independent hardware AI module. Relying on this module, the D2 supports two major capabilities: AI super-resolution and dynamic frame interpolation.

Of course, these features can also be achieved through the Snapdragon 8 Gen 5 Ultra. But the independent D2 chip, much like a discrete graphics card, can “offload” SoC computing tasks during heavy workloads, reducing reliance on the SoC in demanding gaming scenarios. In other words, the addition of the D2 chip further improves the K90 Pro Max’s performance in gaming and multimedia use.

From theoretical performance testing, the REDMI K90 Pro Max scored 4.02 million on AnTuTu, unquestionably belonging to the first tier of Android performance flagships. In Geekbench 6, it achieved 2512 in single-core and 10893 in multi-core performance—again placing it among the top Android performers. Notably, to manage the heat output of the Snapdragon 8 Gen 5 Ultra, REDMI equipped the K90 Pro Max with the “strongest-ever REDMI cooling system”—a 3D Ice-Seal circulating pump with an ultra-large 6700 mm² heat dissipation area (compared to 6500 mm² on the K80 Ultra) and a dual-step dual-circulation structure, improving maximum thermal conductivity to 7W.

In the 3DMark Wild Life Extreme stress test, the K90 Pro Max maintained around 6000 points during the “platform period,” with 81.7% stability. In a 15-minute Genshin Impact test, the average frame rate remained stable at 60 fps. As for the AI super-resolution feature, its overall experience remains similar to that of the K80 Ultra, so we won’t elaborate further here.

In terms of cameras, the REDMI K90 Pro Max’s main camera uses a 50MP Light-Chaser 950 sensor with a large 1/1.31-inch sensor size and a massive 13.5EV dynamic range. In actual performance, both the main and telephoto cameras deliver excellent sharpness and atmospheric bokeh. Even when shooting directly against strong light, leaves do not show obvious ghosting or purple fringing. However, the camera is not perfect: likely due to AI scene recognition, the K90 Pro Max tends to show strong saturation, and in some cases oversaturation leads to detail loss. It’s undeniable that highly saturated photos look vibrant, but they can lack texture and nuance.

For battery life, the REDMI K90 Pro Max features a 7560 mAh Xiaomi Jinshajiang battery with a high energy density of 881 Wh/L. Under normal usage, charging once every two days is achievable. Additionally, the K90 Pro Max supports 100W wired fast charging and 50W wireless fast charging, with wired charging also compatible with 100W PPS.

Bringing true 2.1 audio to a smartphone
Now that we’ve covered the surrounding specs, it’s time to discuss the “core selling point” of the REDMI K90 Pro Max—the BOSE 2.1 triple-speaker system jointly developed with BOSE. Typically, to achieve landscape stereo sound, a smartphone needs two independent speakers—one on top and one on the bottom. To reduce cost, some brands merge the top speaker with the earpiece and designate the bottom full-range speaker as the “main speaker,” producing what they call “bass.” But in the extremely limited space at the bottom of a phone, a full-range driver cannot be physically large enough to produce true low-frequency extension.

But the REDMI K90 Pro Max is different. Rather than simply using a larger driver, REDMI and BOSE designed the K90 Pro Max’s audio as a complete system project. First, the K90 Pro Max uses a three-speaker configuration: two 1115F ultra-linear speakers placed symmetrically at the top and bottom, delivering true high-quality stereo sound. On the back of the phone, a 2016 dual-coil speaker is installed, using the expanded coil area to increase effective vibration area, thereby improving airflow pushed by the low-frequency driver within limited space and dramatically enhancing bass performance.

But hardware is only part of a sound system; enabling all three speakers to cooperate and “use their strengths” is equally important. To achieve this, REDMI designed a dedicated crossover system that builds a complete audio mapping structure through digital audio technology, achieving true 2.1 sound. Based on this, BOSE also contributed deeply to the tuning process, developing two sound profiles: “BOSE Classic” and “BOSE Balanced.” In real-world experience, the K90 Pro Max’s audio performance can be described as “stunning”: whether listening to music or watching videos, it delivers clean and energetic sound with a wide soundstage. In terms of bass, the K90 Pro Max has depth and impact comparable to a Bluetooth speaker; placing the phone sideways against a wall further enhances the bass through the triangular cavity behind it, making for an excellent viewing experience.

Overall, the REDMI K90 Pro Max is a smartphone with strong all-around performance and a very distinctive personality. On one hand, REDMI’s performance-oriented heritage helps the K90 Pro Max establish itself in the fiercely competitive Android flagship market. On the other hand, the BOSE-co-developed 2.1 triple-speaker system brings unique differentiation among “performance flagships” and “camera flagships,” helping the K90 Pro Max stand out. And with a starting price of 3999 yuan, the device is indeed attractive.

From a deeper perspective, the REDMI K90 Pro Max’s unconventional product strategy brings a fresh idea to the smartphone industry, especially to competitors in the flagship category. After all, “audio and video go hand in hand,” and sound is equally important for a smartphone’s multimedia experience. Instead of over-competing in a single saturated field, competing in a new field that still provides real value to consumers can also earn their applause.