Got FHT (variation of FFT) to work on an Arduino with FastLED.

If you want to use it on post-amp like from a home stereo system, here is a circuit for this:

True but you need the additional chip and pcb circuitry whereas FFT is code so setups are so clean with an arduino only. The whole point of this was to remove the MSGEQ7 from the equation since I had really poor quality control results with them and way too expensive

I just meant the 100K stereo pot, the 10K trimmer and the 3.9K resistor. Then you can use FFT on post-amp.

Cheers!
p.s. cheap MSGEQ7 knock-offs are not good. All my parts from Sparkfun are working fine.

Oh I see what you mean, yeah thanks for that very useful