Upgrade from modified Bluesound Node 2i and linear power supply (LPS) ?

USB vs Coax issues aside, The OP is curious as to the sonic benefits of moving up to a Lumin U1 mini. I also have a Node 2i with an outboard DAC and am considering my streamer upgrade options as well. I heard from a dealer that Lumin is going has discontinued the U1 Mini due to a chip shortage. So that means only stores with current stock or buying used are the only options. Also, a consideration should you need service and "that" chip is the issue. Maybe Lumin has a replacement unit in the works and maybe there is another digital streamer worth considering.

In all of my testing, I have always gotten an improvement in sound quality when I upgrade a switching power supply to a linear power supply -- as long as it's a good linear power supply.  The Sbooster has been communicated as a very good power supply.  A really excellent power supply in my testing is the Farad Super3 (but avoid the Synergistic Orange fuse upgrade).  Keces is another good one.

Thanks @audiotroy for the benchmark article. I read it from beginning to end and was impressed with the complete explanation of the quirks of audio signals. Now, if i could only see some of this information listed on amps. or even DAC's. (I have the Denafrips Pontus II after upgrading from the Ares II.   

@txp1, I really enjoyed the Chord Qutest before I got a TT2. It’s a great little DAC! When it comes to streaming music, I’m all in on Roon so I got a Roon Nucleus to stream Tidal and Qobuz. I have it powered by a 19v Sbooster LPS that definitely helped to improve sound quality. I use an iPad Pro and an iPhone 13 Pro Max as remote controllers. 

I have the mobile fidelity board upgrade and lps.. And the streamer is as good or better than the linn klimax renew it replaced.... I first used a chord qutest but have since changed to a project rs2 dac (more for i2s to cd transport)  Both great. The project dac can unpack MQA too. But to answer question seperate lps makes a huge difference.

https://www.fidelityaudio.co.uk/psu-and-interface-378-c.asp