My opinion FOSI Audo is winning with hardware, quality and price. Having 1 linear power for my FOSI stack would be great.
I agree with 3. No need to make any changes, just plug the Q8 power cord into the purified AC output port of PSU20?
I have the ZD3 in bypass because of the ZP3 preamp and ZA3 amp in my setup. I am using the Virtual HiFi supersonic V2 op-amps in the ZD3. The sound quality is relative.
I did not swap the op-amps in the ZP3, I use the pre-amp as a switcher for an ipad, turntable and tv. The ZP3 XLR outputs to analog to digital converter to the ZD3 DAC (bypass), which has the virtual hifi supersonic v2 op-amps. The ZD3 XLR outputs to ZA3 XLR inputs out to Audioengine passive...