I connect to another power socket, still the same noise from speaker.

For you information, our in house technician already tested the 2 units faulty M1370 for more than 1 week, the speaker working fine and doesn't produce problem you encounter.

the sound from the video sounds like open ground issue. if it is, then no doubt the dealership cant replicate the issue at their site. my other speaker used to give this sound at some time of the day, indicating it is really sensitive to electricity changes (voltage drops or spikes).

all i can say, try to bring it to your friend house and check if the humming sound exist. if it is, then your electricity line is not to blame.

well in that case, i guess, there is something wrong inside it. if i were you i probably check for ground loop issue, by touching the metal parts of the subwoofer / speakers. if the humming is gone, it's it. (beware of electrocution!) not blaming your electricity this time, but it could be bad solder job inside the subwoofer.

if all else fail, it's probably bad batches of M1370 you got, or just plain bad luck or both.

Dear alvinfks78,

Sorry for the inconvenience cause.
Please give me your address, i will arrange courier service to pick up your speaker and i will follow up with the technician once the speaker reach my office.

Have you tried to clean up the connector on the speaker input and your source output? Also try to keep the signal cable away from power plug about 5cm or more.