Yep! As far as I know Yamaha was the only manufacturer to use a floating ground system. Korg and Roland, from what I can remember, used a common ground system.

Gary
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PSR-S950, TC Helicon Harmony-M, Digitech VR, Samson Q7, Sennheiser E855, Custom Console, and lots of other silly stuff!

K+E=W (Knowledge Plus Experience = Wisdom.)