MacBook Pro or PC soundcard

Doggie, they use those interfaces because they are better than spdif. Notice how they absolutely keep away form usb as that would be just silly.

I thank the highend transport world in helping make my point. USB is just sily,

*sigh*

USB is a PC based protocol. A transport is NOT a PC. On the PC, you merely use the USB connection to provide an isolated SPDIF/I2S interface (depending on the implementation) as well. Just that it is further away from the noise of the PC.

FWIW, Empirical Audio also provides a USB-I2S interface on their off ramp. If your DAC supports it, it is a better interface than SPDIF.

Doggie - my point is USB is just bad. If it were good, transports may use them. You have to agree the idea of a transport implementing a jitter collector like USB is crazy. USB is like a bellybutton. Eveybody has one. Lets not confuse the industries attempt at functionality and trying to make something easy with saying it is the better protocol. It is actually the worst. Have you heard a good sound card implementation compared to whatever usb dac concoction you are using? I have compared most every one and people actually scratch their heads then they hear the soundcard over usb. Lets leave it as this - agree to disagree. I am qiote confident that in a year or two, USB "high end PC" audio will be non-existent and there will be quite a few used usb interfaces on the market - really cheap.

Yes USB is not perfect. It was not designed for audio.

But how could one get audio from PC? With an internal soundcard? That's an even worse solution due to the EMI inside the PC. With a PC's SPDIF output? That meant you used optical (higher jitter) or coax (higher EMI interference from the computer system)?

First generation examples of USB-SPDIF devices and USB-DACs were not great. But they did outperform many "onboard" soundcards that were susceptible to computer noise.

The second generation of USB-SPDIF/I2S devices like Wavelength's Wavelink HS and from Empirical Audio made an even bigger leap sound quality wise.

It would be silly to go back 3 generations to an internal computer soundcard.

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.