You might want to consider Schitt's Bifrost 2 Multibit. Same price as the D90 but fully user upgradable, both in firmware and software. DAC obsolescence is almost guaranteed given the pace of development in DACs. It is generally acknowledged that the D90 measures exceptionally well but the BF2 has a better sound. Let your ears (and only your ears) be the judge of course but for me, upgradability is important in DACs.
J.Cip
J.Cip