The mystery unfolds with the Spec sheet and it states:
"Robust, impact-resistant, all-steel 2U rackmount chassis Not available in USA, Canada, China, Japan and other 100 – 120V countries"
MX2500: ~230–240VAC, 50–60 Hz, 500W @ 8 Ω
MX3500: ~230–240VAC, 50–60 Hz, 1000W @ 8 ΩAC Connector: 3-pin IEC
What a brilliant piece of engineering by Mackie
. Talk about shooting yourself in the foot.