ZOIA – Empress Effects Inc.。How to power the Empress ZOIA with the correct voltage and polarity?。How to power the Empress ZOIA with the correct voltage and polarity?。Universal 9V, 2.5A Negative-Tip Power Supply – Empress Effects Inc.。ZOIA by Empress EffectBonus:+ Boss Power Adapter (ZOIA compatible)+ USB (5V) power adapter (ZOIA compatible)Firmware version 5.0 and fully functional.The USB adapter is very convenient for traveling.Slight scratches on the bottom right (see picture).