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Is the whine in the audio continuous? or is it intermittent, or dependent on circumstances?
Such whine in audio is usually from feedback.
Is there any way this could be caused by feedback?
Such high-pitched whines or howls or squeakings, in audio systems, are usually caused by feedback of some sort.
What microphone has input to the system?
Classic feedback is produced by a microphone picking up audio output from the same system the microphone feeds into.
Is there any such thing involved here?
What equalizer did you add to the Yasue FT1000 ?