Accuphase E600 voltage conversion

@imhififan

I have converted the voltage to 120v. All is good except for one thing.

I used the 3-prong US power cord (the one with ground prong) to test.

When the amp is on and no music is played. If I stand close to the speakers, I can hear the white sound from the speakers.

I suspected this has something to do with ground prong so I removed it and tried again. The white noise disappeared completely. I played some test tracks for 3 hours and found the sound is exactly the same as when the amp was on Japan voltage.

I wonder if there is any way to fix the white noise issue with the ground prong?

Thank you.

Please note that, I filled the K3 and K4 holes with lead to strengthen the board. 

@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?

@imhififan I just came home from work and test. 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. 

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.

@imhififan I disconnected all sources and connected each one at a time, I found that the DAC produced noise the most. Other sources did have some noise but much less. 

What concerns me is with another amp, the noise level from the DAC is just about 50% compared to with E600. 

Currently, I am using the Accuphase APL-1 power cord, which doesn't use the ground prong. The E600 is dead quiet. The AP-1 power cord is a great power cord, it's a big jump from generic power cable.

However, it would be great if I could use other 3-prong hi-end power cords with E600.