Yep !
My Xpander\ufffds transformer also hums a bit and did since I buyed it new,- but it\ufffds not in the audio signal as also not a ground loop.
PeWe
Am 09.12.2012 14:42, schrieb WT:
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I gather that it is an acoustic hum.\ufffdThis is the transformer vibrating.Try tightening the screws or possibly use some rubber gromets to isolate the transformer from the chassi.\ufffdWT\ufffd