+1 for LUMIN streamers. I too use a Mac, a 2014 vintage MacMini with a 4-core I-7 processor. A few specifics.
The improvement in clarity and the timbre of instruments was very noticeable. I went from (1) a direct USB connection from the MacMini to my DAC to (2) Ethernet from MacMini to a Linksys Ethernet switch, then Ethernet from the switch to the LUMIN, and USB to my DAC.
A second point is that my DAC, pre-amp and the rest of my system are capable of a high level of clarity and resolution. My DAC is an Ayre Acoustics QB-9 with the Twenty upgrade, and I use an Ayre Acoustics K-5xe pre-amp. Both of those units cost between 50% and 75% more than the LUMIN U1 Mini. My Ethernet cables are by Audioquest, but were not overly expensive (about $150 each at the time) and the USB cable from the LUMIN to the Ayre DAC is a Transparent cable.
While I believe there can be further improvements to my system by going to a dedicated music server vs. the MacMini, and by upgrading my cables and Ethernet, having tried some such tweaks I found the improvements marginal compared to adding the LUMIN streamer. The LUMIN and the Ayre DAC have excellent USB interfaces compared to many if not most comparable products. I think the upgrade that may make the most sense for me is to go to an optical Ethernet system, which I will consider at some point. Optical is inherently less prone to noise than copper wires.
I can also say that to my ears the LUMIN is noticeably superior to the Node 2i, the version I demo'd. I can't speak to the new iFi or Project streamers. As always one's budget has a bearing on the final decision.
Happy listening.