Hello,
If you emailed us (Linear Tube Audio) the serial number, we could tell you more exactly. The other easiest method is the color of the screws. If you have red screws on your amp and power supply, it is a "MicroZOTL2 Deluxe". If you have silver screws on your amp and power supply, it is an "MZ2-S" with improved internal wiring in the amp and a higher performance power supply. If you have different colored screws, red=Deluxe and silver=MZ2-S.