Thanks for the tip. So you basically daisychained the C7 power cord with the existing wall wart using various adapters?
Exactly. It goes: Wall Outlet -> Power Cable -> Adapters -> Wall Wart -> DAC.
Whatver magical properties a power cable imbues are now being applied to the wall wart power supply and DAC.
As to how a power cable matters, that’s a whole ‘nother topic. There is a forum post called “Why Power Cables Affect Sound” that has over a dozen pages of discussion. One hypothesis that came up a few times is that a good power cable rejects AC noise and EMI interference. Could that account for the increased performance of the DAC? Perhaps.