I did, it's why I asked since USB 3 supplies 900mA of current. One of my USB 2 ports on my monitor supplies 1200mA. So I guess the 32 led count is limited via firmware regardless of the amount of current available at the USB port.
At 25%, 32 leds in this configuration are drawing a little over 15mA of load each. In theory, if 900mA is available at the port, it should be able to run 58 to 60 leds at 25% and still have some left over as long as the circuitry can handle the load.