High Pitch noise on Active Speakers

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Will try to explain as precise and as short as possible:
Using a Edifier S351DB (S350DB "black version").
For the last few days, every time I switch on the speakers, a high pitch noise, which sounds like is coming from the tweeters, occurs.
The noise slowly reduces, but still there.
The only scenario where it doesn't happens is when the output is on OPT.

Tried different cables, different power plug/socket. Same issue.

As the speaker isn't grounded, I don't think is a ground loop. It happens even with the PC off and no cable connecting them.

As for headphone, if using the port from the Creative Sound Blaster Z, some interference occurs if the GPU is under load. Won't happen if connected at the front panel, which is connected to the same Sound Card.

Before start packing things and requesting some unnecessary RMAs, any suggestions?

Yes, I could simply keep connected with OPT, but the ability to change from speakers to headphones on the fly is a must for me.

I'm not sure the sound card is adding anything to justify it's use.
Is there any sound card that does the automatic switch from OPT to headphone on the fly?

 

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Given this I would say it's something internal on the Edifiers.

Is it happening on both left and right speakers?

Regarding noise from the Creative sound card when GPU is underload, this is probably interference from the GPU. All I can suggest is moving the soundcard as far away (on the motherboard) from the GPU as possible. Unfortunately that sound card takes it's power from the motherboard, and it's also possible the interference is coming via the motherboard power.

Happens to both sides.
As the noise doesn't happen of output is OPT, I'm tempted to change sound card and get the Creative G6. Does it works as a passthrough?

 

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When i bought the 351 I had to return it because of the same fault. If you look online you'll see it seems to be quite common with it and the 350 (I didn't know about it at the time of purchase)

Looking now, yes, there's plenty of people unhappy about that, which seems to be plaguing that model.
I may try and use it with OPT output as last resource.
Just out of curiosity, which speaker are you using now?

 

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As the G6 has a OPT in and out, I was wondering if the G6 would work as a bridge, the OPT out to the speakers, and just plug the headphone when needed.
Thanks for the reply.

 

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The annoying thing is that it only happens with analog signal, won't happen on Optical or Bluetooth.
I was in contact with Edifier and the shop from where I bought the speakers.
As expected, according to many customer's feedbacks, no reply from Edifier. Typical manufacturer you buy their product and hope you never have to deal with them.
The shop, on the other hand suggested few tests. None solved the issue.
They're happy to test it and offer a replacement.
As I just ordered the Creative G6, and will be using OPT for headphone and speakers, I'm not sure the problem will show at some point.
But, as the speakers are about 2 or 3 months old, I stand a better chance to get a replacement now than days before the warranty is due to expire.
Will try and send to them at some point in the next few weeks.

 

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The issue with mine is the speaker, more specifically the amplifier in it.
Tried disconnected from PC, another mains, even tried at my brother's today, just to make sure there's nothing causing any interference.
Using Optical was fine, until yesterday, when the last noise-free input started to show the same issue.
Packed everything today and sent back to the seller who will confirm the issue and replace it.
I was surprised mine was only presenting the issue when the input was analog. Most users facing the same issue with this model happens across all the input.
Fingers crossed the replacement comes working as expected, and fast. Not looking forward using headphones all the time.