Welcome to the forum. I've replied on the Khadas one - again having the schematic proves useful. I doubt there's any benefit from an external supply instead of USB power given the use of multiple regulators, both linear and switching, on the Tone Board, but it would be interesting to see any measurements.
Yes I saw your answer .. thanks for your response!
From what you can understand I don't have technical knowledge! I am just trying stuff (and making errors may be) that I happens to own or have access to!!
Since I have a diyer friend who had some LPSs that could be used we tried... and because of the strange behavior of the board I stuck with it!
Probably you are right and there is no significant difference so no need for extra expense for LPS etc ... but for the sake of "science" we/I experimented to the point we could!
I am planning to lent it to him for some time so that he can take his time and perform some tests.
I don't know if we will be able to record or publish them though!
For the "simple" LPS I think it would be possible to give the schematic for the others I think not! One of them is a commercial product -so I can't and don't have any to give- and the other is diy but I guess the designer doesn't want to give the schematic that open!