The CPU-Z utility confirms that the AmLogic S905X has four (4) cores that run up to 2.02GHz and the processor can put cores at idle if they are not required:

Here is our system setup:

• TV: Panasonic 55CMX710E (4K +3D capable)
• A/V Receiver: Yamaha RX-V775 (7.2 capable) with the latest firmware installed
• Wifi Router: TP-Link VR200 (802ac,b,g,n) with the latest firmware installed

For the tests we used many audio/video files from KODI Wiki

HD Audio Tests (Audio Output at Box set to HDMI Passthrough)

The NexBox A95X supports HD-Audio for only up to 5.1 setups and by using the internal video player. Unfortunately, KODI HDMI-Pass through needs improvements and hopefully NexBox will take care of it with a firmware upgrade. If you choose the software decode, you will get PCM (2.0) only. We also noted that during playback with the internal video player, either the DD or DTS logo was appearing at the top right corner of the screen.

Video Bit rate Tests

For this test we used a test file available at this page. The player was tested with up to 400Mbps files using all the possible sources:

Using USB/LAN/Wifi asa source for our test file, the player's playback limits with does have upper limits with H.264 and H.265 files with 110Mbps were 110 Mbps and 60 Mbps, respectively. Things were tougher for the player with LAN and Wifi file sources.

4K Tests x264 (AVC)

Using the internal videoplayer, the NexBox A95X managed to playback most H.264 files without any issues. As we saw earlier, the player will playback up to 110 Mbit files, so files encoded at higher bit rates will result to jerky playback. The included KODI 16.1 performed better but there is stillroom for improvements.

4K Tests x265 (HEVC)

The NexBox A95X had a a great performance with H265 videos, and was able to deliver perfect playback using the internal Video player. On the other hand, the KODI 16.1 player has some problems, probably due to the fact that it is able to properly decode 8bit files and not 10bit files. Note that we also tried KODI 17 beta and the player's performance with H265 files was much better and without the issues we encountered with the 16.1 build.

4K VP9 Tests

The VP9 codec is finally supported by the AMlogic S905X chipset. The KODI 16.1 software gave perfect results, while the internal video player needs some tweaking.

Other formats

As you see above, we got perfect playback for the older formats (Xvid, DivX, DivXHD). We even tried more rare codecs like the VC1 and the Hi10P.

The ISO format isn't playable using the internal video player, while KODI 16.1 also seems to have some issues with the DVD-ISO format (probably due to the audio track of the tsst file). As a note, if you want to have non-english subtitles with the internal player, make sure they are encoded in the UTF-8 format:

Regarding the 3D support, you should manually select 3D (either L/R or B/T) through the internal player in order to get things done.

The KODI 16.1 doesn't work well and we couldn't get the 3D file was not automatically recognized.

Benchmarks

Read/Write Tests

Moving on to the important read/write tests, the player scored the results you see below for various read and write tasks through the ES File Explorer, using external storage devices and moving/copying a 716MB file:

Obviously, the USB is the best option in order to get the highest performance. The WiFI performance of the player is very poor.