I too use the U2 Mini and believe it performs well for streaming. I did want to ask you if you’ve heard any noticeable noise through your system while listening to the Lumin. Since owning mine I can recall (2-3) times where I’ve noticed what seemed to be a high pitched sound coming from the speaker.
This usually occurs while listening at a lower volume and interestingly is only noticed on the right side. When it occurs I’ve paused the playback and muted the playback briefly and it stops. I’ve also muted the playback and increased the volume and upon lowering it again and unmuting it stops. I first thought this to be a tube but it only occurs while using the Lumin.
I was wondering if you’ve experienced anything like this while listening to yours or if you were only considering the PS upgrade in favor of a linear power supply