I had the HA-1 for just over two weeks and I feel it's a good value for money desktop DAC/Amp. I did quite a bit of comparison with my Invicta v1.0, there are differences DAC-2-DAC feeding to an external amp (ZDSE) despite both being ES9018s.
In addition although the HA-1 amp's portion is decent, (not talking about $$ and return on value or the moment) there is room for improvement in the amp. If I ever bought the HA-1, I'd be more inclined to use it as a DAC-only feeding to an external amp of my choice.
Going back again to the DAC-2-DAC, despite both line out to the same amp, the Invicta's ES9018 implementation is a little more fluid, tonally balanced, & spacious than the HA-1's ES9018 implementation. Of course price wise it's not fair to compare the two & the return on investment, the improvements in the Invicta is not 4x the price of the HA-1 but nevertheless even DAC-2-DAC they sound a little different despite the same DAY chip. Implementation around the DAC is as important as the choice of DAC itself.