Roon is a popular music player, and not just among those using Macs or Apple devices. You can pay for it by monthly subscription or by purchasing a lifetime license. (I shall refrain from commenting on the value of the lifetime license as I’ve not used Roon myself). You can also see what it’s like with a free trial.
There are many advantages to using Roon. It can be used quite simply, with it just installed on your Mac, with the Mac then connected to your D70 DAC, and your amp and headphones. But it can also connect to other devices, including network storage devices and streamers, and it has integration with music services like Tidal and Qobuz. See here: