Well, I was able to get to try the U1 in my system this weekend. I agree with mrcypruz, it is better - don't know why (!) But it is. For me the difference is worth the extra cost. More refined, better highs, most as was previously described, but I'll try it this way. Like most good digital I've heard, in terms of upgrades, it just seems to put everything in its place better, in terms of the presentation. It's not just a factor of sound attributes (e.g., highs, timbre, dynamics, etc.) But of a more realistic presentation. And I think it is also in the realm of timing somehow. As an analogy, compare a 1960 movie in Technicolor - nice looking, but a modern movie in HD looks more like the real thing. The U1 mini sounds a little stunted in comparison. I had the SBooster as well. I also like the idea of being able to keep the U1 for a long time while being able to upgrade the DAC only, if desired, or like in my case presently pairing it with a great SACD player with DAC input.
