So my initial plan was to use a Teensy 3.2 as the brains of the operation - it's fast, lots of I/O, and mostly arduino-library compatible.

Note the mostly. Turns out the library I use for the LCD display, U8Glib, is incompatible with the Teensy, and there's no current fix. The new version, U8G2, is also incompatible. So now I'm stuck shoving a bajillion sensors and connections onto a poor Arduino Nano. Looks like I might have to make this thing dual-core after all! Use something small - like a Trinket - for the LCD display, and control it via i2c from the teensy. Or perhaps use a NodeMCU, so I can at least have one controller do the wifi and the LCD - I know the library works on that.

I've also been working on getting a graphic equalizer running on the LED matrix, but the MSGEQ7 is proving to be a lot harder to deal with than I thought. It wants a very small voltage as an input - such as LINE-IN voltage, rather than an amped up voltage that you get from a microphone breakout board. So I'm playing with a bunch of ideas trying to get it all to work.

I do have a rather impressive rat's nest of wiring going though!