There's not much of a need of a future proof dac because usb is always going to exist, and music higher than 24 bits of quality probably won't matter with a very low priced, or possibly high priced DAC. I don't see fiio products somehow just not working on new computers. I don't know how fast people think the tech world is moving, but usb has been around and will continue to be around as its implementations are constantly improving. Future proof is just a buzz word to attract customers and I don't really see it as anything more than that. I can' see the concern with drivers not working in the future though, but centrance supplies dac solutions to so many good products that it's not really a worry anymore. Besides, spdif doesn't seem like it's going away anytime soon.
Centrance describes their dac products as future proof because you don't need a driver to run them, so they work on any version of osx or windows, and will continue to do so in the future.
Schiit bifrost is described as future proof because it has a drop in slot that could be used for future technologies.
As far as headphones I'd suggest open as well. From what I've read most users seem to prefer sennheiser over beyer for classical, but I'm not a classical fan however I would choose the senns as well if I did.
