Question Edifier R990BT hisses via cable, but not via Bluetooth, what can it be?

[dx151]

It hisses only when audio goes through AUX/2xRCA cable. Silent via Bluetooth. Doesn't matter the source - PC, phone, tablet, laptop - hisses with all of them. And it's not the quite and barely audible hissing sound that most tweeters make, but this one is very, very noticeable. Replacing AUX/2xRCA cable didn't help. Also, hissing happens only when something plays. And the loudness of hissing also doesn't increase or decrease with sound level, remains constant through all sound levels.

I made a stupid move and bought them without deep reviews read and it turns out seveal people complained of that same problem there. No, I can't return it at this time (long story) and I don't want to use Bluetooth because of the slight delay.

Given that I'm not the only one complaining about it - is it fixable at all or this is some built-in low-quality component somewhere and I just have to live with it? Is it grounding issues? Maybe dried capacitors?

 

[Lutfij]

The hiss could be due to a grounding issue or the cable you're using is damaged internally. See if you can take your speakers over to a music store where they have high quality audio cables and see if they can let you try out some cables.

Would also be a good idea if you took your existing cable to the store I speak of to see if you can hear the hiss. If you can't then your power source is the issue, not the cable.

 

[dx151]

The hiss could be due to a grounding issue or the cable you're using is damaged internally. See if you can take your speakers over to a music store where they have high quality audio cables and see if they can let you try out some cables.

Would also be a good idea if you took your existing cable to the store I speak of to see if you can hear the hiss. If you can't then your power source is the issue, not the cable.

I used two different cables (the one that came with it and another I bought separately) and hissing is still present. The new one I bought is very high quality, it's shielded from interference and it still hisses.

By power source you mean my wall socket or the power supply inside of the speaker itself? Thanks.

p.s. the plug itself doesn't have any ground line, just standard L and N. Could this be the whole problem?