Quick little review: I've had this for a little over a year now and it's spectacular. It's my personal end game. No issues, plug-and-play. The balanced output on this is where it's at; sound separation and stage are where this amp excels.
KethI wouldn't question it too much. I've heard the THX is about as good as it gets with a balanced stand-alone amp. But I haven't heard it so I can't compare. I've only compared it to my Audio-GD NFB 11.28 and iFi iDSD Micro Black Label as well as the Cayin iHA-6. To me it has better separation and sound stage than any of those. It has a great, detailed, kind of "cold" or "industrial" sound, which probably doesn't make sense. But it pairs great with my warmer headphones such as Mr. Speakers Aeon Flow Open and Fostex TR-X00. Plus great power and features. I originally looked at this because the 100% balanced structure with dual AKM chips and class A amp.
I may even pick up the THX in addition if it comes back and I have the money, as I've heard it's a pretty stellar amp for the price. I can use the Gustard's DAC and it would be fun to compare.
KethAs Jason noted, don't question the choice of going THX. If you haven't done so already, get a balanced DAC and use it with the THX. I have my THX amp paired with the VMV D1 and it's a great pairing (Elex headphones).
pslayer1Massdrop is working on a matching balanced dac in the same form factor. So my little Grace SDAC will work for now. There aren't nearly enough stand alone DAC's on the market.
KethThat was just the Airist R-2R and that thing doesn't have balance out. Although I would like to see a higher end Grace Design too. They could make a M920 with a newer chipset in the THX 789 chassis.