Teensy 4.1 anolog signal to FFT to 8 pins out ( noise floor help)


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Hello I'm doing an art project that involves sending the max amplitude of 16 different frequency bins at a flashing binary rate to 2 octocouplers in order to achieve 24v (solenoid valves on/ off, one octocoupler has 8 pins each) via digital pins out on the teensy. I'm a technician by trade not an engineer or programmer. I've been using chatgpt 4.0 to help code. Octocouples have LED indicators. So far yes the LEDs flash to the rate of max amplitude of each frequency range. ( 0 to 20k hz) I just have a 3.5mm jack stripped and plugged via mono to one of the teensy pins ( set to anolog in the code aka pin 27) and to ground. But I have too high of a noise floor especially with the first LED ( 0 to ~1.2k hz). Upon reading.. do I need an audio shield? Components, resistors? What's this type of filtering called? I'm just powering through USB. Would using a simple voltage regulator Power supply? Is all this my problems or is there a simple solution I'm missing!? Thanks for the help!
Big picture.. I'm making an audio spectrum visualizer with 128 bands that moves pneumatic cylinders up and down. Using ableton split the recording tracks into 8 instrument clusters that go out 8 different audio outs and the plan is to go into 8 different micro controllers each processing there own FFT all adding up to 128 unique bands. Tried arduino at first. My conclusion was that it didn't have enough memory to do an fft for 16 different bands so I switched to teensy