Sound quality differences between NAS units

[winxi]

(20-08-2016 12:01)simoncn Wrote:  In this case, how do you decide about buying equipment? If you are considering a possible change to your system and you audition a new component that you are considering purchasing and you hear an improvement, do you buy the component based on your audition or do you wait until you have found a review containing the results of an oscilloscope test that proves the new component has superior measurements to your current equipment?

If you always wait for the lab test before buying, your approach is consistent. If you would buy some other component (such as a renderer, amplifier or speakers) based only on an audition. I don't understand why you wouldn't do the same for a source component such as a server.

My point here is that I'm sure that there is no causal link between sound quality and a different NAS and that's why I say that I could only be convinced by a lab test. But of course it's not your job (or the job of any other customer who is obeserving sound quality improvement) to provide such a test or a prove. But I would request such a test before buying from a manufacturer or vendor who claims that his NAS improves sound quality. Do they provide such tests? If not I think they may have good reason to do so.
I would not request a lab test for products which obviously affect sound quality like renderers, amplifiers and speakers. There I rely on data sheets and also personal listening tests.

Quote:I mean if the DAC receives a different input, it might produce a different output. Remember that the DAC is not receiving "ones and zeros" but an analog electrical signal that is encoded in such as way as to convey digital information.

The signal passes through various stages in the renderer before it comes to the DAC. The network interface demodulates the received signal and converts it to 0s and 1s which are buffered in a volatile memory. An internal logic (which is driven by its own clock, btw) fetches the buffered data and applies it serially to the DAC. All these stages contain various active digital comparators which are designed to produce a stable output signal. Also, a good DAC is designed such that its ouput signal does not depend on the input signal level, as long as the input signal level is in well defined limits.
However, since the DAC is the interface between the digital and the analog domain, it has some inherent sources of error and noise and its performance is determined by its design. A great majority of people who have some experience in electronics engineering will tell you that the DAC largely affects sound quality and that, on the other hand, it is extremely unlikely that noise generated in the NAS makes it to the DAC to such an extent that it noticeably affects sound quality.