The Sony X900F and X940E differ mainly in their dynamic range, motion technology, sound, design, and smart TV system version.
1. Difference in the X-tended Dynamic Range PRO (6x vs 10x)
The use of a full-array local dimming backlight on the X900F leads to its dynamic range capabilities being up to six times that of standard edge-lit TV without local dimming. The X940E also has a full-array local dimming backlight but its dynamic range is broader than the X900F because the X940E is capable of up to ten times the contrast range of a conventional edge-lit TV without local dimming. This is due to the X940E having more local dimming zones than the X900F. Besides the more precise light control in different areas of the screen the X940E is able to exert (thus being less affected by picture artifacts related to the dimming such as blooming), the peak brightness in small specular highlights is higher on the X940E than the X900F since the backlight zones are used not only for dimming the backligh but also for boosting it. The higher peak brightness extends the dynamic range so that the HDR (High Dynamic Range) content is rendered more faithfully (although tone-mapping is still used depending on the cd/m2 level HDR10 is mastered to).
2. Different Motion technology (X-Motion Clarity vs Motionflow XR)
Even though both the X900F and X940E have full-array backlight with local dimming and boosting zones, only the X900F utilizes the zones in order to individually tailor the backlight blinking to the motion that is happening on the screen in order to improve the clarity of moving objects without darkening the entire image (which occurs when the entire backlight is scanned). Instead of a black frame insertion the X940E’s Motionflow XR 960 performs (depending on your settings), the X900F’s X-Motion Clarity works by blinking the backlight only in a portion of the frame (where motion is concentrated). This provides a break in the light output so that the moving object doesn’t appear blurred while the rest of the frame is unaffected, and may receive a brightness boost if needed. Other than that, both the X900F and X940E are able to show smooth motion thanks to their native refresh rate of 120Hz and the utilization of motion compensated frame interpolation (the latter is user adjustable).
3. Sound (full-range driver vs 3 way speakers)
The sound system is 2 channel on both the X900F and X940E. That being said, the speakers on the X900F are full-range while those on the X940E are three way so there is a tweeter, mid range, and woofer instead of the X900F’s singe full-range driver. A bass-reflex enclosure is used on the X900F in order to make up for the lack of a dedicated driver for the low-frequency sounds. However, both bass and treble are more pronounced on the X940E due to the dedicated drivers for the low and high frequency range in comparison to the X900F. The total audio power output is 60 Watts on the X940E vs 20 Watts on the X900F. It should also be mentioned that the X940E’s front facing speakers are able to project dialogues and voices more clearly in comparison to the X900F’s down-firing speakers.
The use of front-facing speakers on the X940E necessitates a certain amount of space on the front of the TV to be allocated for them. The X940E solves this problem by staggering vertically the two slates that its panel is comprised of. The X900F doesn’t have front-facing speakers so it doesn’t use the two slate panel structure. Although the stand is different on the X900F vs X940E, a cable-free front can be achieved with both TVs by routing cables through the legs of the X900F’s two-part L-shaped stand, or the X940E’s centrally mounted stand (that still has two support columns). A clean rear look, however, can only be achieved with the X940E because of the utilization of rear panel covers. Furthermore, the X940E features a geometric pattern on its entire neutrally-colored back panel except for the central rear cover which has a leather-like texture. The X900F omits the geometric pattern on the back and its rear panel is black.
5. Smart TV System (Android 7.0 vs 6.0); Firmware
The X900F and X940E both have 16Gb of on-board storage albeit not all is available for installing apps. The reason being that the smart TV system, which is Android 7.0 Nougat on the X900F, and Android 6.0 Marshmallow on the X940E, takes up a certain amount of space. In terms of firmware, there is an update available for the X940E that, among other things, brings support for A2DP Bluetooth profile and Hybrid Log-Gamma HDR format, as well as making the X940E compatible with Amazon Alexa devices (sold separately). The X900F supports the aforementioned features out of the box. When it comes to Dolby Vision support, however, the X900F is expected to be updated by summer 2018 (according to Sony) while the firmware update for the X940E has been released. This update enables Dolby Vision from the TV’s streaming apps but not from Ultra HD Blu-ray disc players (or other devices connected via HDMI to the X940E). These devices also require a firmware update in order to be compatible with the Sony’s implementation of Dolby Vision.