On another note, whilst comparisons between high end expensive usb, streamers, mass storage and any kind of transport solution is all relevant; we want to get an understanding of how different technologies ultimately compare. But I think that the asking price of each solution should also be taken into account more; this helps people to make value-for-money judgements.

Of course, the best value-for-money would be just to plug some IEMs (that probably came free with our cell phone) into our pc. But in reality, unless we really do have more money than we know what to do with, I think that most of us just want to understand the best compromise, for us. We want to know what level of performance we can expect to get for our available funds. And also, how much we'd need to spend to make a worthwhile improvement. So, cost also has some relevance.

There are a lot of ways to skin the proverbial cat. Based on my own experience, I happen to think that the "CAPS" style DIY server provides very good value for money if you have a very capable USB DAC or converter, and your music collection is under 4TB. The basic componentry is only a few hundred dollars, remote interface options are excellent, extensive house wiring via Ethernet is not required, and you can add additional components as funds allow. New improvements can also be added in as they become available. If a better USB card comes along to beat the JCAT, you can just swap that in. With traditional components, things are not nearly that easy.

DIY servers can also be configured to stream via network storage if you would rather do that, or if your music collection is too large for a local hard drive, but obviously that removes any advantage vs. a network renderer such as the Aries, Rendu, or NDS, at least in terms of practicality.

Another alternative is ordering a pre-built music server, some of which are more like conventional computers, some less. You're not going to be able to build your own Aurender W20 by ordering parts from Newegg, it's almost completely custom hardware. I'm sure it will beat a CAPS style server, but I don't know to what degree. They also are not using some off the shelf sound card, so if you don't have a good USB DAC, you may get much better results from a custom music server or network renderer.

My guess is that something like the QA661 will probably sound better than the typical un-optimized Macbook or PC laptop connected to a USB DAC, or some otherwise off the shelf computer powered by a switch mode PSU. That puts the onus entirely on the DAC to fix all of the incoming problems. Optimizing the PC may swing things in the other direction, but then your $250 Linux box must now become a $1200+ Linux box - twice the price of the QA661.