Most of the recommendations about hardware are, for me, overkill.
All in all, it depends on the final processing chain that you require and the number of zones you stream simultaneously.
Since my requirements are at the low end of the spectrum - mainly flacs, 16/24 boys, 44/48 kHz, my hardware is not as powerful as most members. I do have a large library though- ~7500 albums.
I have run it on an I7, on a 2009 Mac mini with core 2 duo, and on my nas with Atom D525.
Currently I run 2 cores - one on my work notebook (i7, 16gb, ssd, win10) and one on the Mac mini (c2d 2.2 ghz, 8gb, HD, win10).
Naturally, there’s a difference in performance when browsing. But I can’t say that browsing on the old machines is sluggish if anything.
Windows is faster than Linux and MacOS.
When streaming the Mac mini doesn’t even break a sweat.
Is it worth the upgrade? That’s for you to say.
If you’re a techie you can try and fiddle with the old machines. I don’t understand what’s there to fiddle with - it’s truly plug and play.