I need some help and your advice will be very appreciated. At the moment, I am using the RPI 4 as end point. The Khadas tone board is connect with the RPI 4 by USB Khadas cable found in the box. In order to improve the sound (actually I am happy with the RPI + DAC but I would like to make some experiment), I want to power the KTB using the GPIO connection. My question are:
If I use the GPIO to power the KTB, can I sill use the USB-C just(link to RPI) to input the signal?
If I use the GPIO to power the KTB and the USB-C (link to RPI) just to input the signal, should the USB cable be without +5V connection (red wre cut) in order to avoid a double power supply or useless connection (which can introduce noise)?
Could you suggest a power supply you know is good in your experience, without pay a lot money? Is the IFI Ipower 5V a good solution? Do you have a better one?
Please could you suggest a good USB cable in your experience? Please do not make me wrong, I do not have any issue with the Khadas USB cable, again I just want to experiment, if you thing it is a good try. Otherwise I will continue to use the Khadas USB cable. In case, I will cut the +5V if it is required.
Do you know if USB cable has to have demanding 90ohm ±15%? Or less is better?
Thank you so much in advance. Thank you for the attention.