JRiver is software that rips (CDs), manages the library, provides a user interface and sends tracks to a DAC, usually via usb. It is a very versatile program but does take a little while to learn. It has volume control so you do not necessary need volume control in a DAC. However, most DACs that are meant to drive a power amp directly have volume control.
Ripping vinyl is another matter. You need an A to D converter and software to process the digital files. You can get a simple A to D like a Tascam DR-5 for $100 or you can spend several thousands. Vinyl Studio is a good program for process the files - splitting tracks, tagging (album name, track name, composers, etc.), and removing noise (pops and clicks, hum, etc.) - cost $29.
Some systems like Sonus integrates with Tidal, but JRiver does not. However, you can just run Tidal on the same PC if you are using one for playback. You can pump the Tidal output into JRiver to use its various DSP modes ( (e.g. tone controls)) for playback.
Don't get too wrapped up in the whole jitter discussion. It is important but clearly a secondary issue. First, you need to decide if you want a full PC solution (like JRiver) and a music server (like the Sony above or a BlueSound solution, or Sonus). Part of the consideration is now good you are with a computer and how much time you want to spend managing your library through the PC.
If using the PC solution, you can then decide on a specific solution. There are several DACs with volume controls that drive a power amp. Or you can get a DAC and an integrated or separate pre-amp or power amp.
I would think about how much you want to spend and how much you want to deal with the computer and go from there.
