I've had an Aqua Formula XHD rev2 DAC for a little while. It's a non-oversampling no-digital-filters DAC. The Holo May I had before was also no-digital-filters when used in NOS mode. Both have a perfect impulse response, no ringing at all. The Aqua makes me completely indifferent to listening to digital or analogue. It does seem a very complicated device and I have no idea how it works. My only concern is that I effectively bought it from the widow of the previous owner, who only had it about 6 months before he departed and she returned to the main dealer.