“Not enough powerful. I had no problem using exactly the same configuration based on a Pi 3 B+ with a small Behringer 302USB mixer, a Yamaha Reface synth and a Logitech keyboard transmitter plugged on USB. But with the Pi 4, the jack audio server looped after a few seconds using 50 % of the processor. I had to use a powered USB Hub to fix this issue. The mixer uses less than 0.5 A, and the synth just exchange MIDI data with the Pi...”