The title is:"There's No Such Thing As Digital..."

Mapman,

Your DAC is not only isolated from computer noise but also from all other nonsense like playback program, file format, computer speed, type of hard disk, amount of RAM etc.

The only thing you could do is to insert reclocker before DAC.

Kijanki,

Yes, I agree and have considered, but hard to justify when things are sounding just the way I want them to already. I may give a re-clocking device a try still sometime in that I am certain I could do even better. It took some time and thought to get to where I am currently. I feel fortunate I have managed to achieve excellent results for relatively small investment so far. The rest of the system makes a difference. My OHM speakers are not hard to get sounding musical to the nth degree in comparison to many. My smaller monitors from Dynaudio and Triangle are a bit more challenging in this regard, but they sound quite "musical" as well and are not my references.

"The whole "gray area" issue(which Hansen eventually admits is not really an issue in a well implemented system), the issue of running multiple processes on the computer, the potential of noise on the grounds, jitter (in all its forms), RFI etc. have been discussed over and over again. A lot of progress has been made on all these fronts with async USB, galvanic isolation, attempts to minimize CPU usage, much better jitter control, etc. Unfortunate, it seems that after several years of figuring out many issues and addressing them, we are now stuck more in a discussion phase than in an significant improvement stage."

There have been some breakthroughs. For instance, it is pretty much accepted that the reason that USB cables make a difference in Async interfaces is common-mode noise. This can be addressed with CM filter or galvanic isolation.

Unfortunately, there are still issues with different SQ from different playback software and different computer hardware when using USB. It makes no sense that improving the power supply for the computer would make a difference, but it does, even with Async USB and galvanic USB isolation. These will remain a mystery for a while I think.

One way to address this is to use networked audio streaming. The downside is that you are trapped into the implementation and playback software. It is also usually limited for sample-rates.

Steve N.
Empirical Audio

Squeezebox and similar devices are essentially specialized computers optimized out of the box to various degrees for playing music. It makes sense to use a computer designed specifically for good sound quality in high end audio applications. General purpose computers can be rigged to work well, but they are general purpose out of the box and not necessarily optimized for high fidelity audio, though I have gotten surprisingly decent results as well in the past by just connecting analog headphone output to the hifi using a decent quality stereo rca to dual rca phono Y connector. The one I have used is also from Audioquest. ITs the easiest way to just get started and establish an initial baseline for computer audio that one can work with from there as needed.

Note that with the analog Y connector approach to connecting computer to hifi, it helps to use a very long wire between computer and hifi. All computers are noisy and you want to keep them as far away from your audio gear as possible. The Audioquest Y connector I've used to good effect is 12' long, for example.