Is your Moon DAC Roon ready? Does it render MQA files? Is it DSD capable? Those are some of the Roon specific benefits of the Lumin.
I have the Focal Clear and LCD3 on a Woo WA5 and WA22 headphone amp. I love the Lumin, and it sounded better than Moon’s stand alone DAC in my auditions. I think the slightly warmer sound of Lumin’s Wolfson DACs would be a good match with the slightly more forward sound of the Utopia.
In terms of streaming sample rate, U1 MINI supports up to DSD256 for a Linux native DSD compatible DAC - but your brand of built-in DAC is not. D2 supports DSD128 sent from Roon but output to BNC is limited to DoP64 only, and some DAC does not support DoP from coaxial input.
In terms of streaming hardware output, U1 MINI offers USB / AES / BNC / RCA coaxial / toslink digital outputs. D2 offers BNC-SPDIF digital output in addition to analog outputs. T2 offers USB / BNC outputs in addition to analog outputs.
I use the same headphone amp, and cans. I have compared the built in DAC to external DACs as my Nagra HD DAC and Chord Hugo TT and to my ears the differences are slight, and the D3 module of the Moon 430 stands it ground when compared with these, very costly, alternatives.
If you are serious about improving the audio you’d need to step up to a streamer with a better DAC than the D2.
And as it happens i recently had the U1 mini in my home for audition! It was getting scrutinized and compared to my Aries G1. While a very good streamer, the difference towards the similarly priced Aries G1 were very small.
When using Roon you basically wont notice, however i deffo prefer Auralics App and GUI over Lumin’s when used without Roon.
Best streamer for my 430HAD? My old MacMini 2010 with Windows and ASIO drivers, putting Native DSD256 into the built in DAC over USB!
(And way cheaper too!) It betters both Lumin and Auralic i’d say!