Mrcypruz, thank you for your comparison, great info. Curious - how did you compare the two? Both connected simultaneously to DAC and quickly switching, or some time in between? USB, coax, etc?
I have the mini and would definitely upgrade if the U1 was better. My logical problem (without testing u1 against the mini) is using my Luxman D08 as a DAC, which is a great CD player, feeding the same 44.1 Hz file through the U1 mini, the CD playback IS better, but not huge. So to buy the U1 to make up only some of that difference doesn't seem to be worth it. I do have a revealing system - Magico/Luxman/Nordost.
I think my way of testing is a good test, using the same DAC via the original CD source as THE reference from which to judge. Most people just using a DAC couldn't do this, obviously. The CD playback presents a performance ceiling that theoretically couldn't be beaten, only strived to, and the Gap is very small in my case at least. I wonder if the DAC receiving the signal from the streamer makes a difference, some kind of synergy issue between two different streamers?