Pass Labs XONO's hum sound

Hi folks,

There is a small hum sound coming from the mid and low driver from my speaker, I then disconnected the input cable but it still there, and I tried to float the earth wire of the power cord still make no different, is this normal ?
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Problem solved by separating both the main & power unit (do not stack).
Same issue with the xp-25. Friggin super sensitive to placement. The Xono is no fussy compared to the xp-25.

The pass phono's hate being close to large tube power supplies.
Do any of these devices have switching power supplies, perchance?