The Mastermind GT draws a lot of current due to its many LCD displays. The backlights of these displays draw varying amount of currents based on the colors being shown. The maximum (with all displays turned white) is around 1600mA. This is a lot more than a typical MIDI controller, so you have to take care to make sure your device can handle that load when phantom powering the GT. Products that are able to phantom power the GT At this time, only our own devices have been successfully tested to phantom power the GT: Amp Gizmo Effect Gizmo (both the original model and the new one with the 6-pin XLR on the front panel) Mini Amp Gizmo Mini Effect Gizmo Rack Gizmo RG-16 Important Note: when phantom powering with our devices, use the GT's power supply to power the device! The supplies that ship with all of our other devices are not able to provide enough current for the GT. Products that known NOT to be able to phantom power the GT Axe-Fx II - it will be damaged if you try! We recommend not using any other device to phantom power the GT unless the manufacturer can confirm that the device can safely supply 12 volts at 2000mA from its phantom power jack. We will be testing other devices and adding them to this list when possible. What to do if my device can't phantom power the GT? The simplest thing to do is to power the GT directly with its own adapter. Just make sure that you never connect it to a power adapter AND a phantom power source at the same time! When it doubt, use a 5-pin MIDI cable to connect to the GT. 5-pin cables will work fine, but will not pass phantom power. We also make a phantom power adapter box. This box has a 5-pin DIN input and a DC power input, which are combined to provide a phantom powered MIDI connection over a 7-pin DIN or 6-pin XLR connector. You can mount this in your rack and use it as the connection point for your GT's MIDI cable. The box will pass bidirectional MIDI, making it ideal for use with an Axe-Fx - or pretty much any MIDI device. What's the difference between the 7-pin DIN connection and the 6-pin XLR? There's very little difference. They both can carry bidirectional MIDI communication and phantom power. The XLR connectors are more sturdy and will lock into place. 7-pin DIN's advantages over the 6-pin XLR are that they're more standard - many products use them - and they're also a little less expensive. We make a variety of 7-pin DIN to 6-pin XLR adapter cables to adapt from our equipment to others'. A note on 7-pin MIDI cables Off the shelf MIDI cables (the ones with black plastic connector housings) use very thin wire, which can be a problem with high current draw. We have not seen a specific problem yet, but such cables will definitely cause the GT to draw more current than it normally would, and this could be a problem in the long term. We don't recommend using them, just to be safe. Using hand made cables with larger gauge wire is recommended. Our cables use 24ga wire internally, which is a larger diameter than any other 7-pin MIDI cable I've seen. We can't go any larger and have it still fit through the back of the connector!