Novice Digital (wired) Question(s)

The first thing you need is a DAC. There are many out there anywhere from $100 to thousands of dollars. I would go with a reasonably priced one from one of the better known manufacturers to start with. You can always upgrade later if you feel the need. The next thing is getting your ripped CD files to the DAC. I would recommend going wireless and use Apple Airplay because you already have a Mac and are using iTunes and your Mac is several rooms away.  If you use Airplay all you need is a 2nd Gen Apple Airport Express or 3rd Generation Apple TV to receive the signal and export it to the DAC. You can do this with an optical cable or coaxial cable. I have been using airplay for my lossless ripped files to an Apple TV or Airport Express for over 8 years in 4 different systems in different rooms and have never had a dropout or any issue. It always works flawlessly.

Going the Apple Airplay route, would you anticipate any appreciable loss in sound quality as opposed to via a cable?  Actually, I’ve been using an Apple TV to more or less do this thru an AV receiver prior to getting the tube amp.  Trouble (?) is that, due to limited inputs on my PrimaLuna Prologue Classic, all such video sources are routed thru the TV, which functions as a switchbox (degradation of signal?). However,... I just happen to have an unused Airport Express lying around.   I guess the only missing link is the DAC then?  One other concern — I’ve digitized a ton of vinyl via Audacity in the form of 16 bit AIFF.  Would this present a problem for a lot of DACs?  Thanks again!

I haven't noticed any loss in sound quality going wireless.

I incorrectly mentioned using a coaxial cable for the output of the Apple TV and Airport Express. I was thinking of something else when I typed that. They do not have coaxial outputs.

I've used the optical output from an iMac, Apple TV3 and Express to systems in my living room, office and garage. The primary limitation on sound quality in the last two isn't Airplay, it's the high level of jitter inherent in the output from the Apple devices. That doesn't mean you can't enjoy the music, I certainly did in all those systems, but if you want better fidelity reducing the jitter is the place to start. 
There are at least a couple of ways to do that, get a DAC (almost certainly a more expensive one) that does a better job of reducing the jitter itself or put a reclocker between the optical output and the DAC.
The Wyred4Sound Remedy Reclocker did a great job in my office system between an iMac and a Simaudio D100 DAC. It made less difference in the living room into a Simaudio D300, a considerably more expensive piece that handled the jitter better on its own. 
In the living room I eliminated the Apple TV as an audio source and now use instead an Arcam rPlay. The Airplay signal goes from my iMac to an 
Apple Extreme router and then via Ethernet to a Wyred4Sound DAC 1. That made for a substantial improvement.
All this to say that I think your effort should be focused downstream of the Airplay signal.