Q: I own a compact M-Audio Keystation 49e, which I can sit on my lap when I’m in front of my iMac (running OS X). Recently, the lights on the front panel have been lighting up, indicating the keyboard is being powered by the USB port, but it’s not triggering synth sounds or samples. I thought it was a driver issue, but I cannot find a driver for this model. Can you help?

A: Under OS X, the M-Audio 49e is fully class-compliant, so it doesn’t require a driver. We’re betting you have it running into some sort of hub, in which case it may indeed be getting enough power to light up the small LEDs on the front panel, but it isn’t actually transmitting note on/note off data. Try plugging it directly into the USB port after a full restart and see if that doesn’t do the trick. You might also try unplugging the hub from the port, then replug it after a full restart.