@m-db, you’ve got a nice problem to have. My first suggestion would be to get the best DAC that you can afford. The best DAC that I could afford in my digital music streaming system is a Chord Hugo TT2. It’s a world-class DAC that you can plug two pairs of headphones into simultaneously, and connect to some active bookshelf speakers that would be office appropriate without taking up tons of shelf space.
For a music server I’d simply get a Roon Nucleus because it has the best user interface on the market right now. Plug an Ethernet cable into it, then run a USB from it to the TT2 and you’re in business. With Apple both units are plug and play. You can pick out almost anything you want to hear using an iPhone, iPad, or a Mac.