What do I need to play ripped CD's?

Is it as simple as putting a Mac, hopefully fanless and with and SSD drive, down in my man-cave, hooking it up to the Wadia via Toslink and controlling with the Apple iTunes remote app?

So to understand, the Wadia is a DAC/CD?  If so, and if the Apple that you are using has a toslink digital output, then all you need to do is rip the CDs and yes, you are good to go.  I am not sure what software program you wish to use to control it from using the tablet, but I would consider Audirvana Plus.  You may also want a separate hard drive to store the files depending upon the size of your CD collection.
  If your Mac doesn’t have a toslink output then you will need to investigate if Apple makes an adapter that can convert an outputted signal to toslink.    If you are committed to the PC route then you may want to check the PC Audio section.

Most Macs of recent years don’t have Toslink output but they all have USB output and that can be used to connect to a DAC with USB input. If the Wadia doesn’t have USB input you could explore connecting via WiFi from the Mac to something like the Audioengine B-Fi which has Toslink output that could go to the Wadia.
https://audioengineusa.com/shop/adapters/b-fi-multiroom-music-streamer/
There are probably other similar Wifi devices. I have an Arcam rPlay that works very well connecting the iMac in my office to the Bel Canto DAC in my living room but it’s no longer distributed.

There are several music applications that can be used to manage your library, Apple Music is included with Macs and works fine but many people prefer Audirvana, as mahler123 recommended, or JRiver.