Hi and i see your points and i agree of course. Also with analog the PS quality is very important.
But still i think much more with digital. I feel that digital is more delicate. The voltage fed to the clock and dac circuits must be perfect. No noise, no spikes. Nothing.
Because most analog circuits have some level of rejection of power supply noise.
Unless they are without feedback i think.
In digital the quartz does not have a PSRR. You feed it badly, it will work badly.
A high precision quartz with a bad PS is a waste.
The only real problem (recharge cycles aside) i found with batteries is the impedance of the batteries.
A good quality and high uF cap close to the circuit can cure this nicely.
The lack of dynamics i think it is due to this impedance not low enough as it should be.
But maybe i am wrong but this is an issue when the circuit draws current in a variable way.
I guess that a USB to SPDIF converter will draw a constant current (maybe i am wrong).
So the not very low impedance could be a lesser issue.
But i have to listen.
But going back to the U12 i would prefer, for instance, a EI type transformer with separated primary and secondary windings to be put outside the box and connected with a shielded umbilical to the U12.
Honestly i am saying this not because i am an expert but because i see the same solutions used by top designers like those in Audio Note
You do not see toroidals in AN dacs for instance
There is also the issue of the transformer mounted on the same pcb of the circuit (vibes) and some magnetic field from the transformer itself.
I wonder if the secondaries are wired in series or parallel.
I mean if a 9-0-9 VAC or a 0-9 VAC are needed.
I will open it in the weekend ... just to peep below the pcb.
Thanks again, gino
