Hello. I use this USB-Y-splitter, and external power supply, with two exit, one to raspberry and one for khadas
In this connection, khadas take power direct from power supply and not from raspberry usb.
But at first boot, sounds have high distortion
To resolve, I must manually disconnect and reconnect power for khadas, then sounds is good
Why?
Ask support.
Seems none mentionned this article.
One USB-C end offers Power Only and the other one DATA Only…
Have you checked which one is concerned ?
Cheers
I see, thanks Gianluca for the pic.
3 “units” concerned : 1 DC 5Vdc - 1 USB-C Female DATA - 1 USB-C Male Power.
What kind of PSU is connected to the splitter ? Cheap DC phone charger >=5Vdc ?
Maybe the AC/DC brickwall adapter is noisy…
What’s your goal using this kind of unit ?
You want more power to fed TB ?
If so, then a DIY cable has been tested for years 
https://www.tnt-audio.com/clinica/221_diy_usb_e.html
Let us know about your investigations 
Regards
This one should works as the USB-Y cable with separately Data and Power.
You might also interesting in:
I use this power supply setting on 5 volt.
But, I listen noise at first boot of system, only if I startup togheter RPI and DAC, powered by the same liner power supply with two exit
But when all components are power on, and I listen noise, If manual unplug only khadas power, and after few seconds, plug again +5 volt to khadas, the sound is good.
I use Volumio software + raspberry pi3+ tone board.
What kind of noise there? can you take a photo to show your setup between the LPS, RPi3B, Tone1 and cables to us?
The audio is strongly distorted and you can hear very low volume this only at the first start of all components.
If after turning on the system, I remove the power supply from the khadas and plug it back in immediately then the sound works
I try now this solution and sound is good.
System all off
1- disconnect DAC from power wire
2- power on supply only for raspberry ( I wait until the software Volumio loaded on raspberry)
3-plug manually power to khadas,.from same power supply
In this mode sounds is good
In other way, when power on DAC and raspberry simultaneously, with the same power supply , I have high distortion
No idea at this time.
Wondering which headphone amp of your setup? And how much impedance of your headphone?
I use desktop amp.
https://www.jolida.com/product/jd-1000-brc
I try different software on raspberry, but same distortion.
The only way to listen well, using dual power , is power on raspberry, wait software startup, and after power on tone board.
Otherwise With normal power from raspberry, no problem
Hi Gianluca,
Seems you’ve got the right way to get good sound.
During computer/SOC/NUC startup, all power sources are stressed, changing state. (Power Good)
While RPi boots, USB port connected is not “ready to synchronise” with TB = distortion.
TB unpluged + plugged back again = good sound (USB sync OK)
That’s what you’re explaining, view from my seat
Gouwa gives some good hints concerning USB.
Enjoy !
Hello Gianluca,
I am sharing same issue with the sound.
I have separate linear power supplies for RPI and Khadas.
For my hardware configuration only solution which helps is to unplug USB cable sourcing Khadas (USB Y splitter) and plug it again.
It is weird. My colleague has similar audio system (similar design) and he is observing no issues.
Gianluca_Battista - Did You find in the meantime another solution to avoid this distorted sound?
Khadas Engineers Team any advices?
Thank You in advance for the support.
Hi
I have separate linear power supplies for RPI and Khadas. What is connecting them finally is Y Splitter (signal from RPi and power from dedicated linear power supply for Khadas).
What is more i have separate switches to turn on RPI and Khadas. My aproach when i turn on the system is same as Gianluca proposed:
No mather what i do and how i change the sequence turn on khadas first or turn on RPI than kadas than turn of khadas and turn on one more time, same result - distorted sound.
When everything is loaded and i manuly unplug the YSplitter from khadas and plug it again sound is pure and clear! Why?!
Why it does not work from the first shot? This unplugging the cable every single time when i want to listen to the music is just frustrating!
Any idea, proposition?
Hi
I want to ask which version is your Toneboard firmware.
Ok! Succes!
I think upgrade improved situation.
Solution:
But why it still does not work from first shot? I do not know.
Hi
If you do not use RPi,and USB -Y-splitter,just use USB A to C cable to connect toneboard to PC,does the noise still exist at the first time?
