I currently own a Bel Canto DAC 3.0 w/BC USB Link, and an Ayre Acoustics QB-9. Both are IMHO incredibly good source components, with very different approaches. Connectivity is not a daunting issue with either.
But if I had your budget of $5K, I'd go as far up the Wavelength Audio foodchain as possible, until it's shown that something betters Gordon Rankin's asynchronous mode solutions, and then spend the rest on your high-res library.
But if I had your budget of $5K, I'd go as far up the Wavelength Audio foodchain as possible, until it's shown that something betters Gordon Rankin's asynchronous mode solutions, and then spend the rest on your high-res library.