Most of the technical discussions about why streamers can sound different focus on issues of noise, jitter, memory buffers, and software implementation, and it is critical to recognize that existing methods for measuring equipment may not do a good job of evaluating differences in streamer sound quality.
I agree with this sentiment, I would also add that the final litmus test is (and must be) the listener, so for people to go on measuring things without listening to them, and somehow being able to extrapolate how the component will sound, is a futile approach.
However, I will say that there are absolutely no audio components I've personally owned which would not be able to withstand the scrutiny of detailed measurements, whatever those are worth. I've listened to plenty of components which were merely ho-hum and boring with no musical enjoyment, and upon inspecting these components' measured results, over time it wasn't surprising to find the pattern - components which measure well do tend to sound better than components which do not.
That being said, just because a component measures well, does not mean it will sound good in your particular application or environment. Too many audiophiles/enthusiasts pay little attention to synergy and integration between components (particularly the room). I laugh every time I see gigantic loudspeakers in rooms entirely too small to support them. The purpose of this pursuit is to enjoy music - the gear is a means to that end. I've listened to countless high end systems and the few that actually play music always stand out - and it's usually because an industry guru spent hours fine-tuning each and every detail in a methodical, logical manner.
As a tangent, next time someone is trying to convince you of a particular direction to take your audio system (i.e. sales person, reviewer, industry maven) I'd suggest asking that individual if they have ever spent any significant time either performing live music as a musician (surprisingly, many have) or has any experience with professional audio engineering (again, many have). In particular, an audio engineer should have some live music experience with sitting behind a mixing desk/console and running a live show (I know some recording guys who are deathly afraid of this which is why I mention it).
The reason I mention this is that the professional audio world tends to have a deeper knowledge of the inner workings of questions like this, which the consumer and "high-end" audio world tend to obfuscate and avoid. The answers are there for those willing to put in the time and the work; if you really want to learn, consider spending the money to obtain an AES membership and delve into the plethora of white papers which can "technically" describe what is happening under the hood with all of these various processes. Unfortunately, what I've seen is that most enthusiasts are simply not interested in this level of research and would prefer to regurgitate misleading or plain wrong information. It's not surprising to me when I've listened to the systems many of these types of folks assemble have absolutely no meaningful communication of the program material and instead represent some fanciful interpretation which seems to suck out the very soul of the music, leaving an anemic shell of a presentation.
Meandering back to the point I originally wished to make - when people provide blanket statements such as "digital is digital" or "as long as it achieves this and that measured spec, it will be fine" simply put their ignorance on display to those who actually know how to assemble a proper music playback system. If they wish to continue to enjoy piss-poor music quality while spending loads of cash on nonsensical ideas, it is their prerogative, but they disservice others wishing to enjoy music at a truly elevated level. I've seen it at each and every level of the HiFi industry, and I won't be surprised when many of the "me-too" brands fade over the next few years while the innovators and pole position brands continue to press ahead and leave others in the dust.
