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Why do different USB ports sound different?

You don't need safety ground to get a ground loop it can also go through mains via leakage currents of power supplies.

You can break a ground loop using the Topping devices or any other real USB isolation devices, Note that some of those devices don't really break those loops.
 
you can hear less noise (like a radio makes noise when it can't catch a frequency), the other sounds dirtier, you can hear noise.
Sometimes noise gets into the analog electronics through the USB power, but that's usually hum, hiss or whine. Sometimes hum is related to a ground loop all of the ports should be grounded the same.

What you're describing might be a short drop-out where the digital audio stream in briefly-intermittently interrupted. Usually one port won't be different from another but it could happen.

The USB port that sounds noisier seems to have more detail in the headphones, more high frequencies, tighter bass. The one that sounds cleaner, the sound with it seems less detailed, the bass is slower and fatter.
That could be a perception related to the noise. Otherwise it's impossible to accidently alter the high or low frequencies digitally. When digital audio gets corrupted (when a 1 is no longer a 1 or a zero is no longer a zero) the sound usually gets terrible. An (imperfect) analogy I sometimes use is that a flipped-bit in bank account is just as likely to cause a billion dollar error as a 1-cent error.
 
If you had some software DSP, it's possible that any settings might not transfer to the device on another port. In practice Windows treats it as a separate device, rather than the same on another port
 
By the way, both USB ports are on the same USB bus, which also has Bluetooth and a receiver for a wireless keyboard and mouse. I disabled Bluetooth, since I don't use it anyway. I found this out from the Windows Device Manager + checked it with the AIDA64.
 
I have an Intel NUC10i5FNH mini-computer and a Topping MX3s DAC. Why does the DAC sound different when connected to different USB ports? Both USB ports are USB 3.1 gen2. This is not self-hypnosis, I even did blind testing to make sure. Which USB port should I choose? The one that I like the sound from more?
Do you have an ADC and software like REW or Multitone Loopback Analyzer? Maybe you can borrow an ADC or maybe someone local to you can test your equipment? If there is an audible difference, it should be apparent on the test equipment.

A cheap and very good ADC is the Cosmos, discussed on other threads.

What is the audio source upstream of the NUC? In your PC software, are you sending the exact same source material to both USB ports? Are the 2 USB ports identical hardware-wise? Are all the drivers up to date? Does the Topping MX3s display show the same sampling and coding format? Have you tried another PC?
 
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Remember that even a cable can create measured differences. In this case it’s with a Topping DAC which is known for a good power circuit.

It’s not impossible to imagine that two ports can have differences, if one is closer to the GPU/CPU.

BUT the other possibility is that Windows is applying different driver settings depending on the USB port being used. It does that sometimes.

Edit: To show hidden devices on Windows, open the Device Manager, then go to View and select Show hidden devices; this will display devices that are currently not connected.

Once you do that, if you see duplicates of your DAC, Windows may be applying different device settings depending on the port.
 
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Remember that even a cable can create measured differences. In this case it’s with a Topping DAC which is known for a good power circuit.
USB cable introduces harmonics and noise? Any explanation about how?
 
USB cable introduces harmonics and noise? Any explanation about how?
 
So, no explanation, great... This is especially interesting because in this test USB cables were not used for power, they were used for data transfer only. Doesn't make sense.
 
Interference in the form of noise, which is abundant inside the small computer case, gets onto the USB bus and then from there via the USB cable gets to the DAC It is possible that some USB port is more susceptible to this interference.
USB is a digital interface. Noise can't apply. Even the jitter discussions are silly when the speed of USB these days is not remotely challenged by any media.
 
So, no explanation, great... This is especially interesting because in this test USB cables were not used for power, they were used for data transfer only. Doesn't make sense.
Agreed. But it’s Amir’s testing so you know it’s good.
 
So, no explanation, great... This is especially interesting because in this test USB cables were not used for power, they were used for data transfer only. Doesn't make sense.
Amir did say it could be the voltage difference/ground loop, and he followed up with a test under better shielding and the result was better.
"This is with balanced output from RME which nicely shields us from the same mains harmonics. We are talking whopping -150 dB or more for the Amazon Basics cable."

Topping MX3s doesn't have balanced output, and USB cables are susceptible to ground loops. Depending on the setup, it could range from inaudible to very annoying pops and cracks. And it doesn't matter if the cable is used for power or not.
 
View attachment 406571

Remember that even a cable can create measured differences. In this case it’s with a Topping DAC which is known for a good power circuit.

It’s not impossible to imagine that two ports can have differences, if one is closer to the GPU/CPU.
Yep, will happen but does not change the sound. It could only add some unwanted noise(s) in a poor performing DAC.
As can be seen the mains leakage adds 60Hz (+ harmonics) at inaudible low levels to the signal in the AB cable but nothing changes to the sound signature.
It is also very clear that the harmonic distortion (nor will FR) change in the slightest way.
The 'added noise' in the wireworld cable is also an 'added' signal (at inaudible levels) but adds no significant mains leakage.

How this pans out on any other DAC in a totally different situation using different gear cannot be shown in these graphs so it cannot serve as evidence.
In any case ... neither cable changes the sound quality nor 'tone' and it simply can't.

The only thing that might happen is added 'unwanted' crap that will not be related to music.
 
Pete Brown from Microsoft talks about how the performance of different USB ports can vary.

 
Do you have an ADC and software like REW or Multitone Loopback Analyzer? Maybe you can borrow an ADC or maybe someone local to you can test your equipment? If there is an audible difference, it should be apparent on the test equipment.
No.
What is the audio source upstream of the NUC?
I didn't understand the question :rolleyes:
In your PC software, are you sending the exact same source material to both USB ports?
Of course.
Are the 2 USB ports identical hardware-wise?
If you mean the USB specification, the answer is yes. Both USB ports are USB 3.1 Gen2.
Are all the drivers up to date?
Yes, all drivers are updated. Downloaded from here. Intel sold its NUCs to ASUS, that's why all drivers are now on the ASUS website.
Does the Topping MX3s display show the same sampling and coding format?
Yes.
Have you tried another PC?
No.
 
Once you do that, if you see duplicates of your DAC, Windows may be applying different device settings depending on the port.
The settings for different USB ports are identical.
 
Turned away from the computer and asked my brother to change the USB port. He played the same track for me. I guessed which USB port was playing 10 out of 10 times.
Scientifically verified blind test is minimum 16 tries in a row, and minimum 12/16 (75%). Recording audio output of the DAC allows easier and more accurate testing.
 
Cool forum! I was hoping for something like: maybe different USB ports, react differently to the noise of internal components such as the motherboard, etc., that's why I hear the difference in headphones. Maybe buying a galvanic decoupler like Topping HS01 or HS02 will help solve the problem. But as a result, they write all sorts of nonsense here. Ok.
May be it would help if you quantified the difference, if indeed it is a noise level or hum this could be explained by a (grounding) connection or the USB power supply.
 
So, no explanation

Try this, impedance mismatch. It could be from the cable to the connector, the chipset driving the cable—on both ends, poor cable construction, poor board layout or simply crap components. All of those can cause noise to be injected into the ground plane of the attached device and increase the noise across the audible spectrum.
 
This is prime head-fi stuff
 
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