The Asus ZenScreen Duo OLED ($599) is a rare portable monitor with not one but two 16:10 full HD OLED screens stacked atop one another. Offering impressive color coverage, this lightweight, portable monitor is best for people who need a pair of extra displays they can take practically anywhere. It’s not perfect—its stand is a little too flimsy, and the glossy finish picks up some distracting glare—but it is a good choice for power users who need lots of extra screen spread but don’t have desk space to spare. If you’re looking, however, for a (single) OLED portable monitor for content creation, we recommend the Editors’ Choice-winning ViewSonic ColorPro VP16-OLED.
Design: Twice the Screen in a Small Package
The ZenScreen Duo measures 8.4 by 12.6 by 0.6 inches (HWD) when folded and weighs 2.36 pounds. It is heftier than other portable monitors like the 15.6-inch espresso Display (2 pounds) or the 14-inch Lenovo ThinkVision M14t Gen2 (1.5 pounds). However, remember that the ZenScreen Duo is two monitors in a single device. Plus, at just over half an inch thick, when folded, the monitor is as thin as an ultraportable laptop. It slips effortlessly into bookbags, totes, and the included carrying case.
Each ZenScreen Duo display is a 14-inch screen measured diagonally (including the bezel); when fully unfolded, the screen reaches a height of about 20 inches. Two hinges hold the monitors together, allowing for a full 360 degrees of movement, not unlike a 2-in-1 laptop. Each of the OLED panels offers a 1,920-by-1,200-pixel resolution and a 16:10 aspect ratio.
(Credit: Joseph Maldonado)
Full HD screens might seem low-res these days, given that 4K monitors and laptops are common. But an OLED panel doesn’t necessarily need a high resolution to impress. OLED display technology outclasses IPS, VA, and TN panels in everything from power efficiency to color-gamut support. OLED monitors can display “true” blacks, which means that the black pixels turn off to create zero-light zones and maximum contrast. This is what enables the ZenScreen Duo to offer a sky-high rated contrast ratio (1,000,000:1) and to deliver wide color range and high color accuracy (both of which we will examine later in the review).
The ZenScreen Duo offers multiple viewing modes to take advantage of both screens. Split Mode uses both screens to offer a “waterfall” view, cascading the image down from the top screen to the bottom one, ideal for coding or reading long documents. Independent Mode allows for two different sources to display their own images on each of the monitor’s screens. Mirror Mode mirrors the source’s output across both screens, and Extend Mode is perfect for when you need extra screen space for simple multitasking.
You’ll find a thin line of ports along the bottom screen’s right flank. The ZenScreen Duo offers a mini HDMI port, two USB-C ports that support DisplayPort output, and an additional USB-C connector that supports the required DC-in cable for power.
(Credit: Joseph Maldonado)
A power button and a return button (for OSD navigation) are nearby, and so is the main OSD control, which is rather finicky. It’s not quite a joystick; it closely mimics a volume scroll wheel in appearance. In use, it operates a little like a rotary phone dial, constantly springing back to center when moved. This leads to some clunky navigation when moving between menus. The monitor includes two USB-C-to-USB-C cords, a mini HDMI-to-HDMI cord, and a little smartphone-style power brick.
Unlike most portable monitors, the ZenScreen Duo includes a 0.25-inch screw-thread socket that enables you to mount the monitor pair onto most camera tripod stands. This might let you, for example, elevate the two screens above your laptop screen in landscape mode. If you don’t have a stand handy, Asus offers its own solution in the $99 Asus ZenScreen Stand MTS02D.
(Credit: Joseph Maldonado)
The ZenScreen’s built-in kickstand is baked into the back of the monitor. A diagonal pattern design cuts across the back and adds a hint of style to the otherwise simple silver casing. It’s sturdy most of the time, but I was particularly cautious when the monitor was fully open beside my laptop—especially when fully extended.
(Credit: Joseph Maldonado)
The monitor also has auto-rotate support, which lets you stand up the two displays in vertical orientation on their narrow edge, with the two panels situated side by side. Note that you need to download the Asus Display Widget to use it (similar to the ViewSonic TD1656-2K’s auto-rotate feature, which also requires software). The auto-rotate feature works only for USB-C DisplayPort connections and is only Windows-compatible. It doesn’t work with an HDMI connection.
In addition to the ZenScreen Duo OLED, Asus offers several other unconventional portable monitors. The ZenScreen Fold OLED has a 17.3-inch QHD display that folds in half, while the ProArt Display PA147CDV has a 14-inch ultrawide display with 1,920 by 550 pixels. Meanwhile, Acer offers the 15.6-inch PD3, which lacks OLED technology but is otherwise comparable to the ZenScreen Duo.
Testing the Asus ZenScreen Duo OLED: Brilliance on the Go
We tested the ZenScreen Duo’s color gamut and brightness using Calman monitor calibration software, a Murideo Six-G signal generator, and a Klein K-10A colorimeter. First, we tested the brightness with the monitor’s default gaming profile over an SDR signal. Under these conditions, it relayed an average brightness of 342 nits (candelas per square meter), close to but not quite reaching Asus’ rated brightness of 400 nits. Moving to HDR, we measured 365 nits of brightness.
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While the monitor is HDR 400 True Black certified, I didn’t notice much difference between HDR content and SDR content on the screen. This may not be an issue for most use cases, since OLED monitors are particularly good at depicting vivid images at lower brightness levels. Plus, the monitor still looked good when watching videos with HDR on or off.
(Credit: Portrait Displays)
Moving from brightness to color gamut performance, the OLED panel earned top marks. In our tests, it spanned 155.4% of the sRGB color gamut (see the chart above), 98.1% of Adobe RGB (see the chart below), and 99.6% of DCI-P3.
(Credit: Portrait Displays)
An sRGB coverage result of over 100% can potentially oversaturate the content you’re viewing, even leading to color inaccuracies when viewing sRGB images. This is particularly true in applications that do not support color management. However, sRGB above 100% exhibits improved color grading and color vibrancy.
The ZenScreen Duo is rated for a peak SDR contrast ratio of 100,000:1 and an HDR contrast ratio of 1,000,000:1. The contrast ratio indicates the difference in luminance between the brightest white and the darkest black a monitor can produce. Ratios as high as these are common for OLED panels; they usually offer a 1,000,000:1 ratio or higher. In contrast (pun intended), IPS panels typically feature contrast ratios of 1,000:1 to 3,000:1.
This all makes the ZenScreen Duo well-positioned for color-specific work. Both of the ZenScreen’s panels support 10-bit color depth, which means the monitor is capable of up to 1.07 billion different colors. Most portable monitors are limited to 8-bit color depth and can display colors from a relatively “small” palette (16.8 million colors). The exceptional color more than makes up for the lower FHD resolution, as well. Chances are, you won’t even notice your content isn’t in 4K.
(Credit: Joseph Maldonado)
In ad hoc testing, both screens looked excellent regardless of the content. Gaming on one screen while playing a video on another might not be the productivity tasks Asus had in mind when developing the ZenScreen Duo. Still, it’s one of the combinations possible thanks to the dual screens.
Both screens, though, can show a lot of glare, depending on the lighting conditions where you are. In PC Labs, the ZenScreen Duo was prone to catching the reflection of the overhead lighting, though it fared better in the dimly lit glow of my home office. It’s something to consider if you will often set up shop at a sunny coffee shop or on a patio.
Verdict: A Power User’s Treasure
The Asus ZenScreen Duo is an impressive display with a specific use case. If you’re already used to having three displays arrayed on your desk, perhaps with some of them oriented in portrait mode, using the ZenScreen Duo will feel second nature. Still, we suspect the additional functionality might be overkill for on-the-go use for all but the most proficient power users. If you’re spending $600, you really have to ask yourself if you will employ that second extra screen to its fullest potential.
(Credit: Joseph Maldonado)
Ultimately, we can confidently recommend the Asus ZenScreen Duo to those who want to maximize their productivity on the go. If you’re looking for just a single extra OLED screen, either of our Editors’ Choice picks is a better option: the ViewSonic VX1655-4K-OLED or the ViewSonic ColorPro VP16-OLED.
Asus ZenScreen Duo OLED (MQ149CD)
The Bottom Line
The Asus ZenScreen Duo OLED is a double-display portable monitor that should delight power users looking to maximize screen real estate on the go.
About Zackery Cuevas
Analyst, Hardware
