It's maxed at 24/96 on the USB out, and 24/192 on the optical SPDIF. Also, my speakers pop loud when I switch my pc on. Once you notice it, it become really annoying, really quick. Playback is usually fine, but sometimes there is a slight skippy noise when I play lossless files through the D1, on the pc, using Roon. The PC is a speedy all SSD / dual GPU / custom watercooled desktop, which I usually prefer over the MBPr (touch bar 15" model) when i'm working at my home office. Another great improvement! My D1 is hooked up to a USB 3 peripheral switch I use to switch it between my pc and mac (together with a mic and mouse). Recently is got Tidal HiFi sub, and discovered Roon. I also bought a set of Audioengine A5+'s along the way, and put a Audioengine D1 Dac + headphone amp in between (USB in, RCA out to A5+'s, 3,5mm to headphones). I ended up buying a Philips X2 first, and last year an Audioquest Nightowl Carbon which I really like. I like it so much that I started researching what makes audio sound better.
I use headphones 80% of the time and started out with a few Senn IEM's until I bought a B&O Beoplay H2 3 or so years ago. I have been listening to AAC files I bought from iTunes for the last few years through iTunes (+iTunes match) on a Macbook Pro and PC and on my iDevices.