I am currently running roon core on a I7 Intel NUC and I am thinking of upgrading. My current path:

I would like to replace my Intel NUC. Some of the options I am considering:
Nucleus
Aurelic Aries G2
Antipodes CX
I would also be removing the SOTM from my setup. In order properly connect the source to the DAC with proper galvanic isolation without the Sotm, what would u recommend?
I am looking to eliminate the SoTM. and connect the Off Ramp 5 reclocker directly to the Streamer/server, so just looking for a better option than the NUC
Look at the SonicTransporter from Small Green Computer. It is less expensive than a Nucleis and offers more cores in the processor (in the i9 version). Some will say that Roon does not use the extra cores but you can get HQPlayer built in that will use the extra horsepower. I upgraded from a NUC i7 to a SonicTransporter i7 about 3 years ago. The SonicTransporter is much faster than the NUC for searches in addition to library processes. Small Green Computer also offers outstanding customer service.
I agree, desktop processors are faster than the mobile processors used in NUCs (including the Nucleus and Antipodes). They are great especially if you are also going to use HQPlayer on the same PC.
That is why I build my own computer for server use.
Supermicro is used a lot in business servers. You can find them in Newegg Business, CDW, maybe Amazon.
I start with motherboards designed for WorkStation use and go from there. Those are not usually small form factor though, and that is fine by me. My last build was based on the Designare Gigabyte board.