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USB Input causes noise across whole amplifier - Musical Fidelity M5si

Hi,
Has anyone experienced this:
 
If a computer is connected to the USB input, the noise level of the amplifier is raised across ALL INPUTS. This is not a 60hz hum. There is an upper mid-range whine/tone and some crackle. This is audible regardless of which input is active. IOW, when using any input, such as AUX2, this noise is present, until the USB cable is disconnected. Apparently there is bleed through the whole system.
 
I have tried different USB cables, USB2 and USB3, USB cable with an incorporated choke. The effect is the same. The noise comes on about 2-3 sec. after connecting the USB cable.
 
This is a new, recently purchased unit.
 
Thanks for any insights
photon_arts
runwell
279 posts
 

If that is the case,do not use the internal DAC.

I have bad experience to use USB port in hifi system,so since then I never use USB port in hifi system again. Now I use optical port,the sound is very good.

photon_arts OP
6 posts
 

Thanks, but this integrated amp doesn't have an optical input.

runwell
279 posts
 

Yes,I know. Just leave the internal  DAC there,you have no way to use it.

Add external DAC if possible.

 

 

tony1954's avatar
tony1954
1,034 posts
 

I have the Musical Fidelity M6si, so I assume the 5si is similar with regards to USB functionality.

From what is says in the manual, I would check that the driver your computer (either Mac or PC) is using is compatible and current and that the computer's settings are correct.

Or just contact Musical Fidelity. They are very helpful and quick to respond.

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