I am in a similar boat as you. My wife and I are now sharing our office and I had my speaker system in the office. I’ve sold off most of my speaker gear and have upgraded my headphone system. I started focusing on headphones a few years ago and have tried quite a few headphones, headphone amps, and a few DAC’s. Currently was just able to upgrade to a fabulous Woo WA5-LE.
For what you are looking for, I would consider a Chord 2Qute or Denafrip Ares DAC and pair it with a LTA MZ2 headphone amp. I’ve worked my way up the LTA line and they are excellent. The way the tube circuit works, it doesn’t put off a lot of heat. The Chord 2Qute is small for your desktop and if I remember correctly it will function as a Roon endpoint even though it’s not officially listed.
Another option if you want to stay in the Bluesound ecosystem and a lower budget would be to get a Hub or Nano and then pair it with a device like the Fiio K13 R2R.
I have not heard the Schiit Mjolnir 3, but it gets very good reviews. It is quite large, but Schiit just came out with what is considered it’s baby brother in the Asgard X. You can even get it with a Mesh DAC card.
One other product that I just picked and am quite impressed with is the Cayin RU9.
Regarding headphones, if you like open planars, you might check out Sash Tres. Two more you might put on your radar are the new HEDD D1 and ZMF.
Good luck with your search.

