Fosi audio k5pro gaming started hissing

[Grandmasteryoda]

Could not find any solution and i dont know if my device is broken, i recently bought a new headphone (dt900 pro x) before i used the dt 990 pro and i did not encounter any issues. Well, the old one broke and i ordered a new pair of headphones. Now i notice that there is a static sound/hiss when i am plugging in the new headphones in my fosio audio k5pro. I muted all volume on my pc and i still got a hiss, when i turn the treble higher with the knob, the hiss gets louder. I thought maybe its my headphone, when i plug the headphone straight into my pc i dont hear any hiss. Than i thought maybe its my pc, so i plugged my dac into the ps5 and still got the same problem. I grabbed some cheap random earbuds i had in my room, plugged them in my dac and still got that hiss sound. So now i know its not my headphone, with my dt 990 that i used first with my dac, i never was hearing that hiss or maybe i just did not notice it. Is there any fix or is my dac broken? I ordered them 1 year ago om amazon. So i should probably have warranty left i think. Please help me!

 

[staticV3]

Hi @Grandmasteryoda! Welcome to ASR.

Different DACs and Headphone Amps have different amounts of noise on their outputs.

Furthermore, different headphones can turn the same amount of noise into different amounts of audible hiss.

This is normal and expected, and certainly no indication that any part of your system is broken.

Here's what I would try:

Plug the Fosi out of your PC, and directly into a good quality USB phone charger ("wall wart"). An Apple charger for example.

Now listen for hiss with your DT900 and earbuds.

If the hiss is gone, then that may indicate that your motherboard's USB 5V output is the problem.

To fix it, keep the phone charger as power supply for the Fosi, and connect the Fosi to your PC via Toslink.

If your PC doesn't have Toslink out, then you can add one with the Hifime UT23 or the Cubilux SPDIF Converter.

If the hiss does not disappear when you plug the Fosi into a phone charger, then the Fosi is simply not a suitable DAC+Amp for your headphones.

As a replacement, try the Apple A2049 headphone adapter.
It's got a supremely low noise floor, and a microphone input if you need it.

 

[Doodski]

Now i notice that there is a static sound/hiss

Can you please define the sound a bit further. Is it more of a 60 Hz buzz or like a snake hissing? How loud is it?

 

[Dunring]

Beyerdynamic 3.5mm to 6.35mm are known for failing, check that first. I've had two fail and testing on the multimeter showed they were bad. One person sent them in for repair and got them back with a dud adapter. Try it using the adapter that came with your amplifier.