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

Very subjective. 

The Weiss Dac 501 is excellent. So are all their products. The minute it was on was a wow. (The 501 is also a Roon endpoint.) That's how I knew.. or was the streamer or something else?

The Grimm MU2 (I have not heard yet) looks to be an excellent one box solution. 

For the kind of money needed to acquire upper DAC's and streamers for a fraction of the cost room treatment and vibration control would be more revealing. Then the DAC, streamer or sound would make yah quake.

Nobody looking at T+A?

Playback Designs MPD-8.

It simply plays music at the highest level of enjoyment.

I no longer think about anything but the music. It's the last DAC I plan on owning.

OP, you work for Infigo Audio. Bit disingenuous (but par for the course here I suppose) for you to ask your question and then answer with the brand you work for.