*DAC

If your equipment supports the AES Standard, then your XLR cables won't make much difference. (if not, or you aren't sure just search for 'Atmasphere' or PM him directly. He can provide great info).

DIY is something you probably don't want to try, unless you have some experience-Not that you can't do it, but there are some subtleties that you should know before undertaking the task. (Perhaps PM @eric squires).

And, to try to keep you from chasing your tail. I think PM'ing John Rutan (Audioconnection) would be the best way to go. 

Bob

@boomerbillone Do you mean Audio Sensibility? Great stuff from them.

@navyachts I owned bluejeans XLRs and still own a set of RCAs. I also own and use Canare 4S11 speaker cables with my AVR and just for 💩s and giggles 🤭 tried them in my main rig. None of these cables belong in the system the caliber of yours. 

Here’s how I would tackle the cable upgrade path -

1. Upgrade speaker cables. Stay with major brands for this system (Kimber, Nordost, Transparent, Audioquest, Audience). I used Audience AU24SX with my Montis and still use them with the Wilsons I have now. You can pick up a used pair for a reasonable price. I would also recommend looking into Nordost Frey 2 or Tyr 2.  I would upgrade interconnects or power cords next. With the length you need for the interconnects it would be more economical to tackle power cords first. You will get a good amplifier of improvement with upgraded power cords. Once again, look for major brands, used. Audioquest Hurricane, would be nice on those amps. Audience AU24SEi works great with digital and is a good deal used.  
But I would start with the amp for power cable upgrade and move up the chain from there. 

Downside with the cable upgrades without having your dac up to the task is that you will hear what it is and isn’t doing right. So you weren’t down to last piece of the puzzle. Hehehe 

OP, You are correct, both of those boxes are combined. My bad. You definitely want just the DAC function. I did some research on sound quality.. and didn’t pay attention to the functions close enough. This price range is not my specialty.

However, for very musical but with detail in the used market I can definitely recommend the Audio Research Reference 9 DAC or maybe one iteration before that. I never thought of ARC and DACs… until I heard one.