MacBook Pro or PC soundcard

USB may have started off clumsily but that's the thing with PC audio. It keeps getting better. The async USB interface from Gordon Rankin and Nugent were big strides in getting to a good quality connection from PC to DAC. Most PCs are full of EMI and RF noise that affects the internal sound card.

Definitely agree it is getting beter. Just not there, yet.

It is better than what you are suggesting though (an internal soundcard).

I've found that a Mac with Audirvana Plus and a decent USB interface is now very close to a disc spinner.

I just thought of something. There are no cd transports with a USB output. They are all spdif (or aes/ebu). Plenty of "excellent" USB dacs, yet no transport mfg has gone with USB. Wonder why? We all know.

It's just wrong ;)

Actually most high end CDPs don't use SPDIF exclusively. A number use I2S or use their proprietary connections with separate word clock.

SPDIF can sometimes result in bad jitter control. FWIW, USB is really about sending SPDIF data over a USB cable instead of a regular toslink or coax digital but with async USB, there's some control over the clock.