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
see pic. In photo, inside this female plug , i put khadasa usb data , then …all conncetion are ok.
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.
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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 !
