This question has been endlessly debated on these forums and many others for years, but that’s ok because it was a new one to me at one point too—until a few wise and knowledgeable folks tore me away from the clutches of Head-Fi, explained some basic concepts to me that after a period of confusion suddenly made perfect sense, and saved me a whole ton of time and money (thankfully). So I don’t mind paying it forward, if others on here don’t take offense.
It’s actually very simple stuff, basic computational math—and it will save you so much time, money and anxiety if you just acknowledge that our ears are very tricky things, and abandon all the standard audiophile adjectives they hold aloft on the fancy forums when it comes to the sound quality of software such as Roon. Why?
Because this is digital audio we’re working with, not analog. Roon provides a bit perfect audio stream to your DAC, with a suite of handy (digital) adjustments available to you to apply before it arrives there to suit your tastes, if you so choose. Nothing less, nothing more.
It’s a bunch of ones and zeros, and has no “sound” by definition—until it gets converted to sound waves that move air. The “quality” it provides you is determined solely by the quality of the original master that was sampled into those ones and zeros at a particular frequency and bit depth, and stored in a FLAC file for you to stream. The rest is up to your amplifier and speakers, which are the only two components in a digital audio setup that add any “qualities” to the sound—in ascending order. This assumes that you’re using a transparent DAC, which basically means any delta sigma unit that was produced within the last seven or eight years (probably more than that).
There are a lot of folks who will argue vehemently that there’s more to it than that, many of whom want to sell you some audio gear, and many more still who want you to buy the same gear they did so they can feel justified in how much they spent. But you’re already on the right track right here with Roon—because it offers you access to a near limitless supply of digital, lossless, soundless files in a nifty package at a reasonable price—waiting for you to convert them back into music. You won’t find any better sounding soundless files to stream anywhere else at any price. Enjoy, and peace 