Likewise, I love my Nucleus+. Elegantly simple and high performance. As for Roon v. Mosaic, I’ve already expressed my choice, and for me, it’s no contest. I applaud the folks who run multiple front-ends. Their feedback is enormously helpful. But having done everything from JRiver (which I detest) to Minim to other UPnP solutions to Roon, I enjoy Roon. YMMV, and that’s what makes having choices so delightful. I have experienced superb, indistinguishable SQ from those other offerings as well. Why? Simple. Bit perfect files delivered over a reliable, low-noise network into an Ethernet port. There is no fathomable engineering reason why UPnP or RAAT should matter. If you think it does, or someone tells you it does, you have to ask yourself “why?”. When I pressed this specific point—why software clients on a network audio system should sound different—Paul McGowan, whom I’ve known for years and is a smart guy, carefully avoided answering (they’re developing a new server and software over there that looks interesting, but it’s not network audio . . . yet). The answer is pretty easy. If you believe network switches all over the world don’t change the sound of a bit-perfect file (and Paul once did a video on that very topic), it’s difficult to maintain that software clients should matter.
I subscribe to the notion that “everything matters.” But one has to be pragmatic. Does cosmic radiation matter much for assessing what temp to cook my steak? Probably not. We can assert that cables sound different, and some people’s ears can prove it in the analog realm, just as some measurements show why some cables sound different from others. I subscribe to that notion. But to me, in the digital realm, particularly Ethernet-based audio, the burden of persuasion is different. It’s easier to demonstrate and verify that the digital information is being delivered accurately to the DAC. Silver and copper aren’t going to affect the validity of that data. It might be possible for a cable or a port or PSU to affect EMI/RF or other noise entering the system, but not the integrity of the musical data itself (unless it is woefully non-compliant). So, if one really does hear something, ask yourself why. It’s far more likely to be perceptual bias, expectation or confirmation bias, or some wholly unrelated problem in the system.
First, @Anupc did not say that bit-perfect and SQ are the same thing. But once one has normalized the delivery mechanism–testing on the same USB setup or the same Ethernet setup—then bit-perfect is in fact a surrogate for SQ in this context. And client software and cables are two very different things. Client software only has one job: controlling what files go to the player. If the file is bit perfect, then it means the client software has not changed the file. If one changes things about the music in Roon or some other software, then the file is no longer bit-perfect; it is different. And as Anup has mentioned, it’s an easy enough test to verify. USB and Ethernet are not the same. And I would submit you don’t in fact need to worry about the Ethernet cable so long as it is certified compliant and unshielded (on dCS equipment). But even if you subscribe to the notion that compliant digital cables can alter SQ (without altering bit-perfect status), nothing about that validates the notion that client software can affect the SQ of a bit-perfect music file. It might cause you to ask, but it hardly proves it.
I know that, as audiophiles, it is so easy to get sucked into the notion that “just because we don’t know how to measure it, doesn’t mean I am not hearing it.” And I agree! But that is only the starting point. It’s not the answer. The answer is the “how” and “why.” Remain skeptical. In both directions. But enjoy the music.