Question Buzzing / humming backround noise when playing games, screeching in headphones when moving mouse, not from hardware ?

[Pappo666]

Hi!

i would have put this in Audio if there was one but i guess this will have to be good enough

i recently went all out shopping spree got basically all new PC first monitor LG 27GN850-B and mobo Asus strix 590 F gaming + cpu 11600K

i noticed some audio dropouts coming from my SPDIF only dac and i read that the 590 is infamous for audio dropouts got a replacement and was still there so i went and bought a USB DAC for 250 ish USD to circumvent the SPDIF while i was waiting on the dac i grabbed a 3060 v2 12gb ram and now with the dac there is a lot of background noise which gets louder when i play games i read it could be coil whine and recommended to limit FPS this helped ever so slightly.

i then read it could be due to a bad PSU and sure the one i was using was 12 ish years old so i got a new one didnt help
i also read that it could be electrical interference due to unshielded cable so i went out and bought an Audioquest USB A - C Carbon for250 ish USD did not help the background noise much but i do have better audio quality...

i also read that it could be a ground loop issue and recommendation was to put all devices on the same wall socket which i already were doing so it cant / shouldn't be that

i have checked windows audio settings (dont have motherboard drivers installed) and enhancements are disabled some ppl say mute mic and line and can not see any of that probbaly due to no motherboard audio drivers

Dac drivers are installed and up to date

i have ordered a 3 meter Displayport cable from Supra that is tripple shielded for 70 ish USD no idea what it will arrive

i also read that some old / cheap peripherals can cause this and recommendation was to unplugg them one by one til the sound is gone i did that and nothing changed

so far my only guess is that the motherboard it self have bad USB ports and will probbaly go and buy MATRIX ELEMENT H USB 3.0 Controller

https://www.audiophonics.fr/en/pc-htpc-modules/matrix-element-h-usb-30-controller-jack-dc-pcie-femtoclock-crystek-power-filter-p-13543.html?search_query=matrix element&fast_search=fs

another thing i been thinking of to try is this but i dont want to cough up 500 USD for something that might not work

nano iGalvanic3.0 by iFi audio - Galvanic Isolation for USB 3.0

One-stop USB audio improvement system The nano iGalvanic3.0 plugs into any USB port via your DAC. It creates a new signal, eliminates noise and jitter and unleashes your home computer’s full potential.

ifi-audio.com

unless someone here have a better suggestion on how to solve this issue? prays coz this is driving me insane

Parts list:

Motherboard: ASUS ROG STRIX Z590-F GAMING WIFI
CPU: 11600K
GPU 3060V2 12gb
Ram: Corsair Vengeance LPX Black 32GB (2x16GB) / 3200MHz / DDR4 / CL16 / CMK32GX4M2E3200C16
PSU: Corsair RM850X 2021
Monitor: LG 27GN850-B
DAC: SMSLSU-6
USB cable from PC to Dac Audioquest USB A to C - Carbon
RCA from Dac to headphone amp: Curtesy cable (next part to be replaced)
Headphones: Beyerdynamic DT 770 Pro for games andHifiman Arya for music (when kid isnt home)
Mouse: Razer Naga chroma
Keyboard: Roccat RYOS (replaced in near future)

 

[Ralston18]

Are you using any surge protectors, power bars/strips?

Any splitters or adapters of any sort being used?

Are you familiar with TS, TRS, and TRRS?

If not, FYI:

https://www.cablechick.com.au/blog/understanding-trrs-and-audio-jacks/

Are you able to provide a simple sketch showing how all of your devices are connected together?

Include all devices, ports, cables, power sources, etc..

If so, do so, and post the sketch here using imgur (www.imgur.com)

The sketch will provide a sense of the overall physical configuration and connections being used.

And we can move your post to Home Audio as warranted.

 

[Pappo666]

Are you using any surge protectors, power bars/strips?

Any splitters or adapters of any sort being used?

Are you familiar with TS, TRS, and TRRS?

If not, FYI:

https://www.cablechick.com.au/blog/understanding-trrs-and-audio-jacks/

Are you able to provide a simple sketch showing how all of your devices are connected together?

Include all devices, ports, cables, power sources, etc..

If so, do so, and post the sketch here using imgur (www.imgur.com)

The sketch will provide a sense of the overall physical configuration and connections being used.

And we can move your post to Home Audio as warranted.

Hi thanks for the reply

yes i am using a powerstrip with power surge protection with built in Master /Slave function so if PC is off it cuts power to all other devices but if that would be the cause then my home theatre and my wifes PC would suffer a similar issue we also replaced it with a cheap non surge protection and it didnt help

Link to the product if helpful
https://www.brennenstuhl.com/sv-SE/...-anthracite-3m-h05vv-f-3g1-5-1xmaster-5xslave

Nope not using any forms of splitter but i am using a 3.5mm to 6.3mm on the headphone cable into the headphone amp based on that link you provided it is TRS as it has 2 rings so do the 3.5mm headphone cable

The sketch toke a little longer then i wanted to but i tried to be as detailed as possible and the link to it is here

https://imgur.com/Ok3QmAG

View: https://i.imgur.com/Ok3QmAG.png


i do apologise i did not see any section regarding Audio and i spent 15 minutes looking

 

[Ralston18]

No need to apologize: the category is Home Audio and Theater.

Thank you for the sketch. Nicely done.

What I look for in such sketches is any possible path for an electrical loop of any sort. A connected to B connected to C connected to D and then a connection leading back to A.

The actual physical path may not be readily apparent especially with multiple devices. Lots of cables and wires be they power, video, audio, network, or otherwise. It can and does become quite a tangle in many situations.

As I understand your sketch, it appears that loops may indeed exist. If not, the fault is mine - not your sketch.

Any wired network devices? Remember network devices: modem, router, NAS etc. all include Ethernet cable as well.

One immediate suspect, my mind at least, is that surge protector. Cutting off power to any sort of electronics can be damaging. And all the more so if such cut-offs are effectively much the same as just pulling the plug. Versus using the device's on/off switch.

Sudden power losses are not good in general and even worse for computers and other smart electronics (even though turned "off") that still have current flowing to them to speed up start times.

Cheap or otherwise those surge protectors tend to be very low quality in most cases. Design, components, assembly, testing (if any at all) are done as cheaply as possible. And remember that surge protectors do not last forever anyway. Surge protectors are measured in Joules and once the joule limit (cumulative) is reached there is no more protection. Could be one big hit or a number of smaller hits.

Start with as basic configuration as you can. Key to "basic" is that there is no buzz, hum, or screeches.

Once achieved, then begin methodically adding back other components one at a time and allow time between additions. Keep notes because you may need to go through the process a few times - adding components back in different orders.

Try to leave out the surge protector if at all possible.

In the meantime, I will move your question to Home Audio and Theater.

Good chance that a member audiophile may spot something.

 

[Pappo666]

No need to apologize: the category is Home Audio and Theater.

Thank you for the sketch. Nicely done.

What I look for in such sketches is any possible path for an electrical loop of any sort. A connected to B connected to C connected to D and then a connection leading back to A.

The actual physical path may not be readily apparent especially with multiple devices. Lots of cables and wires be they power, video, audio, network, or otherwise. It can and does become quite a tangle in many situations.

As I understand your sketch, it appears that loops may indeed exist. If not, the fault is mine - not your sketch.

Any wired network devices? Remember network devices: modem, router, NAS etc. all include Ethernet cable as well.

One immediate suspect, my mind at least, is that surge protector. Cutting off power to any sort of electronics can be damaging. And all the more so if such cut-offs are effectively much the same as just pulling the plug. Versus using the device's on/off switch.

Sudden power losses are not good in general and even worse for computers and other smart electronics (even though turned "off") that still have current flowing to them to speed up start times.

Cheap or otherwise those surge protectors tend to be very low quality in most cases. Design, components, assembly, testing (if any at all) are done as cheaply as possible. And remember that surge protectors do not last forever anyway. Surge protectors are measured in Joules and once the joule limit (cumulative) is reached there is no more protection. Could be one big hit or a number of smaller hits.

Start with as basic configuration as you can. Key to "basic" is that there is no buzz, hum, or screeches.

Once achieved, then begin methodically adding back other components one at a time and allow time between additions. Keep notes because you may need to go through the process a few times - adding components back in different orders.

Try to leave out the surge protector if at all possible.

In the meantime, I will move your question to Home Audio and Theater.

Good chance that a member audiophile may spot something.

yes ofc it has internet i totally forgot about that...

Now a while later it hit me that maybe Ethernet cables carry groundso maybe i should mention that the router and the PC is connected on different wall sockets

this sketch wont be as good as the previous one that my wife did as she is currently not home

https://imgur.com/Xkme6h6

View: https://i.imgur.com/Xkme6h6.png





me and the wife was speculating if it could have been the power strip / surge protector and we did replace it with a standard strip with no surge protection and only hooked 1 monitor, PC, dac and amp, mouse and the backround noise was still there this to me show its not that
and i normally shut things off manually before i power off the PC so it dont kill the power while the devices are powered on i do this to minimise the "standby"

where would this loop be if it exist and how would i go about solving it? i been over my connections over and over and not seen anything (but i also dont really know what im doing)
from what i read the powerstrip should have one ground from the wall and then all devices plugged into the strip share the same ground so from my understanding this should not cause a loop?

basic configuration i did do this when i replaced the surge protector as almost nothing except the dac / amp, monitor, mouse was hooked up did not change anything

and if i should not use a surge protector what is your opinion regarding these "AC power Filters"? been ogling one for a while now to get clean power to the devises

such as this one
https://www.audiophonics.fr/en/mult...rt-schuko-gold-plated-gold-plated-p-5587.html

 

[Ralston18]

First: Regarding the AC power filter - hold on that unless and until "dirty power" is truly proven to be an issue.

[Side note: Especially a product with only 2 reviews of any sort.....]

= = = =

As for the common grounds - who knows? Something may have failed and no longer be as thought or expected.

You mentioned shielded cables. Shielding is necessary in some environments but rarely so in a home/residential environment. Plus if shielded cables are used they must be properly grounded to be effective. And possibly problematic if not grounded.

FYI:

https://www.quadrangleproducts.com/what-is-the-difference-between-shielded-and-unshielded-cable/

(You can easily find other similar links.)

Note Item #5 under "Guidelines for Effective Cable Shielding"

" 5. Ground the cable at one end. This eliminates the potential for noise-inducing ground loops."

= = = =

When you "go over the connections" (which is good) you must do so in a manner that starts with a buzz, hum, and screech free starting point or base configuration.

It is certainly troublesome to have to disconnect everything and start over.

Still, as I understand your environment, that is what needs to be done.

You now have your diagrams. Combine, correct, and otherwise make the diagram as representative as possible.

Make a couple of extra copies and use the diagrams to manage various connections/re-connections. Check off problem free connections and configurations. Then move on to the next set. You can control the reconnect order in what ever logical manner seems applicable. Plus try in some other order as well.

Establish some minimal hardware configuration where all works without any buzzing, humming, or screeching.

If the noise continues with just the basic PC, monitor, keyboard, mouse, and audio peripherals then the number of potential culprits are greatly reduced.

 

[Pappo666]

First: Regarding the AC power filter - hold on that unless and until "dirty power" is truly proven to be an issue.

[Side note: Especially a product with only 2 reviews of any sort.....]

= = = =

As for the common grounds - who knows? Something may have failed and no longer be as thought or expected.

You mentioned shielded cables. Shielding is necessary in some environments but rarely so in a home/residential environment. Plus if shielded cables are used they must be properly grounded to be effective. And possibly problematic if not grounded.

FYI:

https://www.quadrangleproducts.com/what-is-the-difference-between-shielded-and-unshielded-cable/

(You can easily find other similar links.)

Note Item #5 under "Guidelines for Effective Cable Shielding"

" 5. Ground the cable at one end. This eliminates the potential for noise-inducing ground loops."

= = = =

When you "go over the connections" (which is good) you must do so in a manner that starts with a buzz, hum, and screech free starting point or base configuration.

It is certainly troublesome to have to disconnect everything and start over.

Still, as I understand your environment, that is what needs to be done.

You now have your diagrams. Combine, correct, and otherwise make the diagram as representative as possible.

Make a couple of extra copies and use the diagrams to manage various connections/re-connections. Check off problem free connections and configurations. Then move on to the next set. You can control the reconnect order in what ever logical manner seems applicable. Plus try in some other order as well.

Establish some minimal hardware configuration where all works without any buzzing, humming, or screeching.

If the noise continues with just the basic PC, monitor, keyboard, mouse, and audio peripherals then the number of potential culprits are greatly reduced.

Done that and no difference, the only time it truely went away was when i toke the headphones and connected them straight to the 3.5mm headphone jack on the motherboard which was odd so i borrowed my wifes USB gaming headset to see if it is bad usb ports on the motherboard and it was still quiet so this to me points to the dac or headphoneamp sadly i dont have any way of testing them individually and no money to just go out and buy a new one

 

[drivinfast247]

Did all these new PC parts come with a full reinstall of Windows? Are you sure of the stand-off locations for motherboard?

 

[Pappo666]

Did all these new PC parts come with a full reinstall of Windows? Are you sure of the stand-off locations for motherboard?

Yes of course everytime a new hardware went inside the case windows was installed

1 or 2 skrews are not skrewed in due to case having the holes a few mm to the side the one next to the 24 pin power connector is for sure not there and there is no standoffs there either i can only assume that modern motherboards skrewholes have moved ever so slightly over the years and my old Silverstone TJ11 does not like that

 

[drivinfast247]

Yes of course everytime a new hardware went inside the case windows was installed

1 or 2 skrews are not skrewed in due to case having the holes a few mm to the side the one next to the 24 pin power connector is for sure not there and there is no standoffs there either i can only assume that modern motherboards skrewholes have moved ever so slightly over the years and my old Silverstone TJ11 does not like that

What is your current case?

 

[Pappo666]

What is your current case?

Silverstone TJ11 its pretty old by now but even now i not found a worthy replacement maybe i will soon if the rumours are true that Caselabs are returning

https://www.silverstonetek.com/legacy.php?area=en&model=TJ11

 

[drivinfast247]

You have something shorting/grounding out in your case.

Try unplugging the USB from motherboard.

 

[Pappo666]

You have something shorting/grounding out in your case.

Try unplugging the USB from motherboard.

Will try that tomorrow as it is pretty late here but how do you get to that conclusion just from the case? if i may ask

 

[drivinfast247]

Will try that tomorrow as it is pretty late here but how do you get to that conclusion just from the case? if i may ask

I was trying to see the specs on the case.

 

[Pappo666]

I was trying to see the specs on the case.

So i did what you said and disconnected the usb front header from the motherboard and it got in a way better and in one way worse so i did some reading and one suggested to someone else to do the same with the front Audio header so i shut it off again and disconnected the front audio from the motherboard and same results a little better a little worse

The way it got better was that the random spikes of the buzzing and humming was gone and at low volume on the amp it was not there at all but when i increased the volume it would overpower the sound how do i explain imagine that i twist the knob 10% then the game sound volume increase by 5% and the noise by 10%

i recently found a thread regarding coil whine which i know i don't have they recommended to limit the FPS in game to 60 and see if that would make it better and since i don't have coil whine from the hardware i didn't bother but now i figured why the hell not its a quick and easy thing to test so i did and the background noise drastically got reduced

and if there would be something with the case or hardware would the noise not be there all the time? i mean i did try my wife's USB gaming headset HyperX cloud II and the sound was perfect 0 noise so to me this should rule out any form of hardware no?

Whats also weird is that i can hear everything that is happening on the desktop like if i open a folder or scrolling a web page etc

so what confuse me is this

Limiting the FPS points to GPU but then the noise should been there when i used wife's gaming headset

Disconnecting the usb front header changed the noise signature a little but was gone with wife's headset so this points to the case

Disconnecting all usb cables except the one that goes to the dac changed nothing

increasing the volume on the amp increase the sound i want at a limited amount where as the noise gets louder this points to the amp

Or am i totally wrong?

 

[Ralston18]

Considering:

"1 or 2 skrews are not skrewed in due to case having the holes a few mm to the side the one next to the 24 pin power connector is for sure not there and there is no standoffs there either i can only assume that modern motherboards skrewholes have moved ever so slightly over the years and my old Silverstone TJ11 does not like that "

Makes me wonder about the screws that are in place......

If the motherboard is not properly in place and secured there will be problems.

Also:

"and if there would be something with the case or hardware would the noise not be there all the time? i mean i did try my wife's USB gaming headset HyperX cloud II and the sound was perfect 0 noise so to me this should rule out any form of hardware no "

So using another known working headset makes the noise go away ("perfect 0 noise") with all other connections and configuration being unchanged - correct?

What is different between the headphones you normally use (Beyerdynamic DT 770 Pro for games andHifiman Arya ) and the Hyper X Cloud II?

 

[drivinfast247]

Your wifes headset is USB and so is the DAC that you used with your other analog headphones. One having issues and not the other is odd.

Please list all audio devices used so far. The make/model and a link would be nice.

Off topic: please return that $250 USB cable. A digital cable either works or it doesn't. An audiophile USB cable doesn't/can't change the sound.

 

[Pappo666]

Considering:

"1 or 2 skrews are not skrewed in due to case having the holes a few mm to the side the one next to the 24 pin power connector is for sure not there and there is no standoffs there either i can only assume that modern motherboards skrewholes have moved ever so slightly over the years and my old Silverstone TJ11 does not like that "

Makes me wonder about the screws that are in place......

If the motherboard is not properly in place and secured there will be problems.

Also:

"and if there would be something with the case or hardware would the noise not be there all the time? i mean i did try my wife's USB gaming headset HyperX cloud II and the sound was perfect 0 noise so to me this should rule out any form of hardware no "

So using another known working headset makes the noise go away ("perfect 0 noise") with all other connections and configuration being unchanged - correct?

What is different between the headphones you normally use (Beyerdynamic DT 770 Pro for games andHifiman Arya ) and the Hyper X Cloud II?

"If the motherboard is not properly in place and secured there will be problems."

i will look into this might need to look up how to make new skrewholes tho which sounds difficult

"Makes me wonder about the screws that are in place......"
The rest of the skrews that was lining up to the holes on the case are perfectly installed

"What is different between the headphones you normally use (Beyerdynamic DT 770 Pro for games andHifiman Arya ) and the Hyper X Cloud II? "

the differance between the Hifiman and Beyerdynamic is 0 and both of those have the same issue the differance between the Hifiman / Beyerdynamic and the hyperX is that the HyperX has a "built" in usb dac as seen on this picture

https://imgur.com/3ezrcqs

View: https://i.imgur.com/3ezrcqs.png

 

[Pappo666]

Your wifes headset is USB and so is the DAC that you used with your other analog headphones. One having issues and not the other is odd.

Please list all audio devices used so far. The make/model and a link would be nice.

Off topic: please return that $250 USB cable. A digital cable either works or it doesn't. An audiophile USB cable doesn't/can't change the sound.

Yeah it is indeed odd that's what i mean that it could be the dac or amp that i use with my Beyerdynamic and hifiman and when i plug those headphones into my wife's usb dac that came with her HyperX its also 0 noise

Audio Device list

Dac: S.M.S.L SU-6 "https://www.smsl-audio.com/portal/product/detail/id/773.html"

Amp: Beyerdynamic A20 "https://europe.beyerdynamic.com/a-20.html"

Headset: HyperX cloud II "https://www.hyperxgaming.com/en/headsets/cloud-gaming-headset"

Headphones Beyerdynamic DT 770 250 ohm "https://europe.beyerdynamic.com/dt-770-pro.html"

Headphones: Hifiman Arya https://store.hifiman.com/index.php/arya.html



Parts that has backround noise

Dac: S.M.S.L SU-6
Amp: Beyerdynamic A20
Headphones Beyerdynamic DT 770 250 ohm
Headphones: Hifiman Arya

Parts that does NOT have backround noise
Headset: HyperX cloud II

Tried to make it as clean as possible to minimize misunderstandings

"Off topic: please return that $250 USB cable"

Will do already thought about it since it did not solve my issue but i can say it did make the sound cleaner and less "muddy" call it placebo or not but my wife said the same but i want to solve the issue with the backround noise before i buy luxury accessories like cables

 

[drivinfast247]

Yeah it is indeed odd that's what i mean that it could be the dac or amp that i use with my Beyerdynamic and hifiman and when i plug those headphones into my wife's usb dac that came with her HyperX its also 0 noise

Audio Device list

Dac: S.M.S.L SU-6 "https://www.smsl-audio.com/portal/product/detail/id/773.html"

Amp: Beyerdynamic A20 "https://europe.beyerdynamic.com/a-20.html"

Headset: HyperX cloud II "https://www.hyperxgaming.com/en/headsets/cloud-gaming-headset"

Headphones Beyerdynamic DT 770 250 ohm "https://europe.beyerdynamic.com/dt-770-pro.html"

Headphones: Hifiman Arya https://store.hifiman.com/index.php/arya.html



Parts that has backround noise

Dac: S.M.S.L SU-6
Amp: Beyerdynamic A20
Headphones Beyerdynamic DT 770 250 ohm
Headphones: Hifiman Arya

Parts that does NOT have backround noise
Headset: HyperX cloud II

Tried to make it as clean as possible to minimize misunderstandings

"Off topic: please return that $250 USB cable"

Will do already thought about it since it did not solve my issue but i can say it did make the sound cleaner and less "muddy" call it placebo or not but my wife said the same but i want to solve the issue with the backround noise before i buy luxury accessories like cables

I'd say the problem lies in that DAC.

 

[Pappo666]

I'd say the problem lies in that DAC.

ok ill run down to town when i get money and buy the cheapest dac they got and see if that solves it

 

[Ralston18]

Am I correct regarding the following?

No Microphone:

Headphones Beyerdynamic DT 770 250 ohm
Headphones: Hifiman Arya

There is noise.

Microphone:

Headset: HyperX cloud II

There is no noise.

= = = =

So the presence of a microphone, if I have followed correctly, eliminates the noise?

 

[Pappo666]

Am I correct regarding the following?

No Microphone:

Headphones Beyerdynamic DT 770 250 ohm
Headphones: Hifiman Arya

There is noise.

Microphone:

Headset: HyperX cloud II

There is no noise.

= = = =

So the presence of a microphone, if I have followed correctly, eliminates the noise?

Yes that is correct The headphones has no microphone while the wife's gaming headset do

but i do not think it is because of the microphone unless you know something i don't

 

[Ralston18]

Ref: "but i do not think it is because of the microphone unless you know something i don't"

Not that at all.

And, per post #7 your wife's gaming headset with microphone did not have the noise - correct? Mic on or off? Make and model headset?

Objective being to simply narrow down the source of the problem one way or another.

Swapping parts, changing connections, elimination, etc..

Could be the dac: purchasing and swapping in another known working dac may well prove that the current dac is the problem. Good that you have that option available.

= = = =

Otherwise:

Establish as basic a "no noise" configuration ( minimum hardware, software, settings) as possible.

Then methodically add to the configuration bit by bit until the noise returns. Then whatever was last done is the likely culprit.

You will likely need to go through the process a few times to be certain and to confirm what ever was discovered.

I am thinking a loop of some sort - where I do not know.

Not sure what else to suggest.

Lots of information within this thread: Hopefully someone else will read through it all and note some error of omission or commission on my part.

I have no problem with that.

 

[Pappo666]

Ref: "but i do not think it is because of the microphone unless you know something i don't"

Not that at all.

And, per post #7 your wife's gaming headset with microphone did not have the noise - correct? Mic on or off? Make and model headset?

Objective being to simply narrow down the source of the problem one way or another.

Swapping parts, changing connections, elimination, etc..

Could be the dac: purchasing and swapping in another known working dac may well prove that the current dac is the problem. Good that you have that option available.

= = = =

Otherwise:

Establish as basic a "no noise" configuration ( minimum hardware, software, settings) as possible.

Then methodically add to the configuration bit by bit until the noise returns. Then whatever was last done is the likely culprit.

You will likely need to go through the process a few times to be certain and to confirm what ever was discovered.

I am thinking a loop of some sort - where I do not know.

Not sure what else to suggest.

Lots of information within this thread: Hopefully someone else will read through it all and note some error of omission or commission on my part.

I have no problem with that.

"your wife's gaming headset with microphone did not have the noise - correct? "

Yes this is correct

"Mic on or off? "

tried both and same result no noise

Make and model headset? Those are the HyperX Cloud II i been mentioning

"I am thinking a loop of some sort - where I do not know."

yeah me neither and i am unsure if there would be any otherway to connect all the devices i been thinking if i should call the landlord to test the wall socket if the ground is even working as it should


it did hit me that a dac is a dac and they all work the same so what i was thinking is when she is done in school i will take the USB Dac that belong to her gaming headset (HyperX cloud II) and a 3.5mm - RCA cable and connect that to my headphone amp andbypass my SMSL SU-6 dac why?

we know her headset works in my PC but we do not know if it is the SMSL SU-6 dac or the Beyerdynamic A20 amp that is at fault since this will bypass the SMSL SU-6 and if that works and produce 0 noise then we know its the SMSL SU-6 dac and if the noise is still there doing this then it is either the Beyerdynamic A20 headphone amp or the RCA cable between the dac and amp not sure if a cable could produce these issues but we know the problem is after the SMSL SU-6 dac but since both my headphones work flawlessly in my wife's PC albeit quietly due to no amplifier we know its not the headphones