Hi,
I had a quick look at the E3631 schematic. The ADC circuitry is much better than the DAC and the rest of the power supply from a precision point of view. For example the TL074 op-amps used in the output voltage control have a typical offset drift specification of 18uV/C. This is gained up by the circuit, around 12, to 216uV/C.
Also the DAC is shared, using a mux and track and hold circuits between 8 outputs. (Tektronix did this in the TDS5xx and TDS7xx scopes. It is one of the things that goes bad if the electrolytics leak on the board)
![](https://www.eevblog.com/forum/testgear/why-hp-using-audio-dac-in-e3631-psu/?action=dlattach;attach=320602;image)
The ADC is much better. It is
*possible*, I don't know, it depends on the firmware, that the DAC is being disciplined by the ADC, so that it doesn't need to be that good, just have lots of resolution.
Regards,
Jay_Diddy_B