How about a Mele Quieter 3. Fanless. J5105 processsor, 8 gig ram, has Emmc memory, but can take up to 4 TB of NVME. I run one as my HTPC. Works just fine, streams Netflix in 4K, HDR 10, runs JRiver w Dirac with zero lip sync issues. Just does the job, completely quiet, works off the shelf, has Windows 11 built in. All for around $260, and there are ususally $20-40 discount coupons out there. Available on Amazon.
Not as powerful or fast as some of the other rigs mention in the thread, but it's powerful and fast enough. Plenty snappy enough as a browser as well. Just don't try to run Final Cut Pro with it.
What % of CPU do you have with JRiver + Dirac Live? I want that and a Focusrite Scarlett ADC with a turntable.
Maybe is too much for that machine.