How to get into high end digital? (Feeding a DAC)

You can use your Nakamichi's coax digital output into the DAC via a Monoprice digital cable. Any CD/DVD player can serve as a transport. No need to spend big bucks! They all output the same data stream! Jitter is a non-issue with modern DACs. No need for a separate - and expensive - clock! Jitter in even cheap CD/DVD players is inaudible. This was a problem solved decades ago! Don't believe the pundits saying that spending ever more on a transport gives "better" sound quality. Not true! Digital is NOT like Analog! The same thing applies to cables. Cheap here works just as well as expensive. A $10 Monoprice digital cable is indistinguishable from a three or four figure cable - regardless of what the "golden ears" crowd claims. 

I will get a lot of flak for my post! But hey, those are the facts of life kids! 

Why Schiit or Topping? For less than $300 you can buy a Khadas 2 Tone Pro Dac that measures and sounds as good as any four-figure DAC! I own the earlier model, the KTB.

I am familiar with your Nak 5 disc CD player. The multiple disk was a nice feature, but it was not near as good as their Tape Decks, but the name sold it. If you want to keep playing your CD's, I would suggest getting a CD transport and feed it into a good DAC, you mentioned two good ones, but everyone has their favorite. However, if you want to get off of CD's, then buy either a Bluesound Vault or an Aurrender and burn them onto the hard drive. If you were used to loading the Nak and playing CD after CD, you will love being able to do it from your phone, laptop or iPad. I was 'talked' into the Bluesound 2 years ago and was glad I did, ever since then I never listen to my actual CD's. Also, the Vault and some of the Aurrenders will get you into streaming in a fast, easy way. Many opinions out there, so perhaps others will suggest otherwise, but this is what I did and it made getting into everything digital easy and quick, and I am still very happy.

You can use your Nakamichi's coax digital output into the DAC via a Monoprice digital cable.

There is only a red and a white RCA, and either it or the RCAs have tinny sound out of the RHS channel.
Hence no coax digital out (it is a last millennium unit).

... Any CD/DVD player can serve as a transport. No need to spend big bucks! They all output the same data stream! Jitter is a non-issue with modern DACs. No need for a separate - and expensive - clock! Jitter in even cheap CD/DVD players is inaudible.

Even if you were wrong, then if the DAC buffers the samples, so we should end with jitter free output after the DAC?? (Right?)

Why Schiit or Topping? For less than $300 you can buy a Khadas 2 Tone Pro Dac that measures and sounds as good as any four-figure DAC! I own the earlier model, the KTB.

I dunno…
If we trust specs, then they are demonstrably good…

But I’ll look at that Khadas 2. Thanks!