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

Back in the day, is when I bought my Ayre QB9 and the emphasis was in how to make digital sound analogue. The technology has changed significantly since then. I was lucky in that Ayre has updated that DAC to the present. Maybe close to eight years ago I bought the Uptone Audio ISO Regen with linear power supply and found that it made a very noticeable difference. Today on my Ayre QB9 Twenty, the difference is minimal by comparison.

The criteria for choosing a DAC today is so much more complex, i.e. detail, soundstage, noise floor, jitter, etc… This in part is due to the DAC chip but more so, how it’s implemented. And because of this, I’d still recommend trying to visit brick and mortar stores to hear as many DAC’s and transports as possible.

I just set up my Brinkmann Nyquist mk 2.  I realize that I now need to get a preamp. I was under the impression I could use the internal volume control, but it guess that's not what it's designed for.  I'm waiting on a new one from a specific manufacturer, so I'll get a used balanced with zero feedback one until the one I want is ready.  Darn me!!!  That's the MS.  I can't always think straight and don't always understand what I read.  I could have sworn a reviewer used them directly to the amps. Oh well... Next piece of gear...:) 

JasonBourne says..‘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.’

LoL! Way to go to get things off to a contentious start! By the way I enjoy your posts and respect your opinion greatly.  On these two areas I would have to offer an alternative opinion though.

A) Digital Transport (for CD) - the Oppo UDP-205, Pioneer BDP-09fd, and Parasound Halo D3 all sound different. Even if the DAC is supposedly indifferent being asynchronous, As far as signal from CD transport, it is not all the same sound. 
B) Digital cables sound very different. The Black Cat SilverStar MkII I received from CFarrow is ultra high res. And provides a super-clear window on the music. The Black Cat Veloce is very good, but not as good as the SilverStar. Less resolving. The Canare is well behind both.

Cheers!

Digital is a very deep and winding rabbit hole but a potentially fun journey.  Long and short of it everything matters which means there's lots of avenues for improvement after you start.

First buy used for best value and return when upgrading.  Get a good DAC, add a reclocker like an IsoRegen, some decent USB cables like Curious, some decent digital power cords like Wywire, some powerline noise reducer like PS Noise Harvesters, then a real music server- start simple line Bluenode and upgrade later and enjoy.

I much preferred my Wyred4Sound DAC over my Yggy,
see: https://wyred4sound.com/products/clearance/dac-2v2se-trade-units
it includes a good volume control.  A lot is made about R2R but the W4S was just better sounding all around.  I traded up to a Denafrips Terminator then TP.  I would recommend anything Denafrips but the used market is small.

Check out US Audiomart and https://audiophilestyle.com/forums/forum/18-buy-sell-audio-and-computer-components/ for used digital gear.