Some facts:

• 256 RGB LEDs
• 768 DMX Channels
• Teensy 3.6 as Main Controller
• ESP8266 as ArtNet Node
• 3 TLC5940s for controlling brightness
• 2 74CH595 Shift Registers for multiplexing

So, this is the second LED Matrix we are building. The first one was a bit smaller (10x10) and used shift registers only for controlling the LEDs. We weren't that happy about the limitation we got using shift registers only. We ran into refresh rate problems while trying to increase possible grayscale values. We ended up with 8bit grayscale (0-255).

The images are from this instrucable. There you can also find more information on multiplexing:

Using ArtNet Node running on an ESP8266. See this awesome project.