@quanghuy147 

If you disconnect ALL sources from the E600, connect ONLY the speakers to the E600 and use a 3-prong power cord to power up the E600, can you hear any noise if you turn up the volume?

When I disconnect all sources from E600, only the speakers are connected to the E600, 3-pong power cord is used, I don't hear any noise even when I turn up the volume to 12 o'clock position.

I believe the noise problem is not the E600, please connect the sources one at a time to test and see which one causing problem.

@quanghuy147 

It seems like some grounding problem between components. Would you provide detail information what components are in your system and how they connected together, maybe we can figure out what is the culprit.

I think you have the similar problem.

https://forum.audiogon.com/discussions/usb-input-causes-noise-across-whole-amplifier-musical-fidelity-m5si

I think E470 has different layout, if you can post a picture of the voltage selection board, maybe I can provide some help on the voltage conversion.

🥂

I'm glad to be of help🙂

@pip555

Can you post the photos directly? Without google account I can’t access to it.

@pip555 

Can you post a picture the back of this PCB?

Not sure if I can help, perhaps from the picture we can figure it out. BTW, are you comfortable of using a DMM on mains voltage? 

@pip555

Thanks for posting those images, for 120V mains, I believe J1 should moves to J4, J3 moves to J5. And J2 remains in the same place.

Before you move the jumper wires, please measure the following resistance and post the result to make sure if the projected configuration is correct:

Black - Brown

Black - Red

Orange - Yellow

Orange - Blue

Measurement should taken from the plugs out of the sockets.

@pip555

Thanks for the measurements, the readings confirm that brown and yellow are 100V windings, red and blue are 120V windings.

You can go ahead to move the jumper wire J1 to J4, J3 to J5. That will change the voltage setting from 100V to 120V.