I have now burned in and listen to the microRendu with both the Ifi Power and the MCRU power supply (with silver cable and fuse upgrade). To me the microRendu (Roon RAAT output) with the Ifi Power was a nice upgrade to my JCAT USB board with JCAT battery power supply connected to my Offramp 5 on most aspects. The sound difference was essentially; clearer and more open overall sound and a bit stronger bass. I distinguished also that the sound got a little bit harder and less smooth, especially in the treble, but also in other frequencies.
When I got the MCRU power supply it only took one day before it sound much better than the Ifi. After more burn in and listening to the microRendu and MCRU combo the SQ improved further in all sonic ways. The sound get even clearer, faster, opener, resolving, and the bass even stronger. The sound additionally, and very important to me, got fuller, richer, smoother and more organic. The earlier small bit of hardness I hard with the Ifi was totally gone. The sound really got better, much better even, with the MCRU power supply to me and with my gear.
In short: The mR with the Ifi was a nice upgrade from my PC that I have used together with JCAT USB + battery power. However to me the mR with the Ifi was just a teaser on what the mR can sound like with a better power supply like the MCRU.
Please keep in mind that I use a tube DAC, those are normally very sensitive to all form of pollution from other gear (which are backlashing noises to the mains power) and that I use a PC in the same room to store and play audio files.