The amp itself sounds amazing, by far the most detailed and musical headphone amp I have owned, and I am using it to drive an AKG Q701 Quincy Jones headphone with custom Cardas headphone cable.
The sound is very clean, and also neutral, with the most wonderful treble extension I have heard. Detail levels are very good, and the build quality and solidity of the amp is exceptional.
In short I am very happy with my purchase, and the fact that it is made in Australia by an Australian company is also a big bonus.
I will probably buy a Burson DAC in the future, to perfectly match the HA-160.