What the Best Dac have you heard or owned. How could you tell it was that good.

I use the AudioQuest Cobalt Dragonfly with my laptop. It's really amazing! I'm also running an AudioQuest cable with it to the preamp.

Currently using the Benchmark DAC3HGC and the AHB2 amp driving some ATC monitors.  There were clear steps up in performance from the Parasound ZDAC, to the Project Pre-Box S2, to the Benchmark.  I really think Benchmark is on to something by using higher line levels, the SN ratio is astounding.  Depth of field, transient response, bass detail, just everything with the Benchmark is better.

@calvinj i trust you have seen my past thread on dacs i have tried/owned... it is by no means exhaustive but given your query it should be of some help

I use my apple dongle DAC more than any other, definitely the shortest signal path and mobile, it’s perfect.  

The most satisfying and lifelike DAC that I’ve heard is the Chord Dave with a Chord Hugo M Scaler using Nick Bacon’s WAVE High Fidelity Storm BNC cables as interconnects. At present I have a Chord TT2 DAC and M Scaler which I’m very happy with. Having retired after spending over forty years in the rat race I no longer have any interest in evaluating audio gear. I would rather spend my time listening to and exploring new music that I haven’t heard before and revisiting my favorite recordings from the past.