A lot of folks out there are taking an older unused computer or even a new MAC Mini and dedicating it to serving their music. This is a good idea relative to using a shared computer to do the same - but dedicating a computer to this task isn't the same as a purpose build server.
Let's take the MAC Mini for example. The MAC Mini from Apple is perhaps one of the best bargains in computers today: low cost, quiet (fanless) fast and has a built in hard drive. Once you manage to install the appropriate software and get the setup right, you can remove the video monitor, mouse and other peripherals and just let it run. Many folks do this with great succes.
But an all purpose computer, like the Mini, is more like a receiver than separates. An all purpose computer is asked to do a lot of things unrelated to serving music and, just like in the case of a stereo receiver, it really never does one thing better than anything else. We turn to separate components for a reason and that same logic applies to computers serving music as well.
Our engineering team is working hard on building a true dedicated server - as I am sure a few other forward thinking high-end audio companies are as well. Our work so far has shown clear and irrefutable results that dedicating hardware and software to one single task provides far better sonic performance in streaming audio than a general purpose device does - and this applies to just taking an off-the-shelf motherboard and dedicating it to the task as well.
So if a manufacturer has chosen to purchase an off-the-shelf single board computer or motherboard and then polish it up with software and peripherals to build a dedicated server - it's still a general purpose computer with all the inherent noise and issues associated with them.
We're approaching an age where we're going to get back to separates and for good reason.