They would have to used the balanced SDAC, which opens up direct comparison to the Monoprice unit with a screen at $479, and that supports optical and coax, as well as DSD.
This unit is differential, not balanced. It is driving a single 789, with differential output, to very impressive effect (outstanding performance measured).
There would be no need for balanced DACs given this pragmatic design approach - indeed the Massdrop Grace Design "Balanced" similarly provides a differential output at the chip pins, rather than a balanced topology; it could easily be integrated for a complete 'differential' chain.
It is a bit of a marketing bait and switch, but the performance justification for differential seems perfectly vindicated given the performance this unit is showing.
So I have the standard Grace SDACm and my debate is between getting this and updating my DAC in the future, or the Monoprice unit and just calling it done for a good while. I already have a solid PEQ in software ( https://sourceforge.net/projects/equalizerapo/ ), but still like the idea of the Monoprice unit or the Stoner Acoustics UDXA as pretty much being endgame for me...I don't have the need to move up to Chord products down the road.
I hear you! These THX amps are a tempting bunch. . . I have been considering very similar options myself!
When advising others, it is easier for me to keep a level head:
The MD THX 789 is a known quantity, and frankly one of if not the best measuring solid state amps in existence. You know the high quality of Grace DACs, as mentioned the balanced Grace MD DAC employs a similar pragmatic differential output approach, so you could make an affordable upgrade when it drops next, and go differential boards / balanced XLR interconnects for the full chain. . .
There should be measurements of the monoprice unit popping up in the coming weeks, so I'd suggest just waiting a bit longer and avoid all risk. Keep in mind it is a combo DAC and amp, so it is not reasonable to expect it to outperform the 789 amp in isolation. If it turns out the Monolith doesn't suit your fancy, the 789/Grace option is still waiting here for you.
For myself? I cannot be quite so reasonable when tempted by toys. I am enamored with a full balanced topology for more philosophical than pragmatic reasons. I've bought a Monolith unit and should get it sometime this week :)
I'm actually using the Grace SDAC with the Liquid Spark at the moment...and the amp has left me underwhelmed, not to mention having a slightly noisy pre amp output to my monitors. So the plan is to return that tomorrow, and then order one of these two units, and a pair of Argons or T60RP's as a chistmas present to myself.
I literally just got the shipping notice on my new pair of T60RP's lol :) Should get them along with the Monolith before the long weekend (fingers crossed)
Sorry to hear the Spark didn't work out, it looked like a really promising amp to me. Best of luck in your hunt for audio goodness!