Most of the Yamaha players I've talked with claim they have no issues with phase cancellation. My hearing is shot to hell, so I couldn't hear it if it was a problem.
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.)