Older post, but just for info.
I use one of these
MeLE Quieter2Q Fanless Mini PC Intel Celeron J4125 8GB DDR4 128GB eMMC Mini Computer with Windows 11 Pro, Micro Desktop PC Supports 4K Dual-Screen Output, Dual WIFI, Gigabit Ethernet, BT4.2 https://amzn.eu/d/2VOcXeA
I rarely see processing speeds go less than 10.0x on Roon. I’d say this is the minimum spec you’d get away with.
I got mine for less that £200 with 8gb RAM. Dropped in a
Hypertec FirestormLite 256GB M.2 2280 NVMe PCIe Gen 3x4 SSD; M keyed https://amzn.eu/d/55KuFkR
The above is faster than the internal storage.
Took a while to set the bios. Installed Roon ROCK.
Plugged in this
AudioQuest - JitterBug FMJ USB Data & Power Noise Filter https://amzn.eu/d/ah1kTGN
And then this
AudioQuest DragonFly DAC USB Digital Audio Converter - Cobalt https://amzn.eu/d/2yM1JDC
Total cost
£500
I have used multiple devices as endpoints such as RPis with Volumio and Allo HATS and find the above used directly sounds good enough for my needs. I have and ATV setup on a TV with another ATV paired with 2 homepods and using the power of HDMI Arc can enjoy music in the bedroom.