I've gotten best results from using an external USB to SPDIF converter (a Trends UD-10) between my Mac Mini and my tubed Scott Nixon TD2 DAC with a '57 Amperex 6DJ8 (Heerlen) and the upgraded power supply.
What really improved things was ditching the wall wart that came with the UD-10 and replacing it with an external, powerful Hewlett Packard power supply set to match the wall wart's specs.
Cabling is a custom Cardas Clear male to male USB to the UD-10, a 24k gold KCI Pegasus to the TD2 and an RCA pair of Omega Mikro experimental, one-of-a-kind, "Planar IX"s (akin to an Ebony with a non-battery-powered "network supply box"). This feeds my Viva Solista SET integrated amp.
Some might say my DAC is the weak link in the chain. However, it's euphonic and musical and I'm not that much into digital, anyway.
What really improved things was ditching the wall wart that came with the UD-10 and replacing it with an external, powerful Hewlett Packard power supply set to match the wall wart's specs.
Cabling is a custom Cardas Clear male to male USB to the UD-10, a 24k gold KCI Pegasus to the TD2 and an RCA pair of Omega Mikro experimental, one-of-a-kind, "Planar IX"s (akin to an Ebony with a non-battery-powered "network supply box"). This feeds my Viva Solista SET integrated amp.
Some might say my DAC is the weak link in the chain. However, it's euphonic and musical and I'm not that much into digital, anyway.