If streaming is your main source, then I would either purchase a Roon core then use your DAC as a USB endpoint, your Arcam irDAC will decode DSD128, which will make a massive difference, you can encode your CD rips to DSD using Roon. If you are confident to build your own PC, then I would go for at least an i5 based NUC with an SSD drive, use the USB input on the DAC. The Roonlabs website will tell you more.
If you listen to vinyl, as your main source, then there are dealers who can customer build an LP12 out of used parts, you could use your Rega arm on a Linn build. I am not allowed to recommend a dealer, before the lockdown situation he went globetrotting building and upgrading LP12's for various customers, an enviable reputation to have.
Upgrade your source first, that will make a larger improvement, rather than your capable amplifier and speakers, upgrade those at a later date.