That's a great point: above some frequency, the inductance of the system starts to average the voltage like the output of a switching power supply. I did think

That's a great point: above some frequency, the inductance of the system starts to average the voltage like the output of a switching power supply. I did think of that: I used a camera with a rolling shutter image sensor and manual exposure settings to prove to myself the LEDs were really still getting the full swing at higher frequencies. Also, to be clear, I'm talking about 12VDC COB LEDs with hard on/off PWM dimming, not A/C ripple. I don't know, but I'd expect the cutoff frequency to be a lot higher. The self inductance of 30ft of 16awg wire is about 20uH. I should test it...