I think in your case there are two things you need to address - first, where are you going to store your hi-res files and second, how are you going to access them for playback on two separate systems.
If you want to minimize purchasing new gear and are willing to experiment with some software on your MacBook Air, then my suggestion is to look into a free app called Kodi (https://kodi.tv/). Kodi can turn your MacBook Air into a media server using a protocol called UPnP (for more information see https://www.cambridgeaudio.com/usa/en/blog/what-upnp). Store all your hi-res files on your Mac and let Kodi do the rest.
If I’m reading the N70ae manual right, Kodi will enable your Pioneer to browse the music library stored on your Mac and stream the file over the network (see pp.19-20 on enabling Windows media sharing which also uses UPnP).
You can connect the Mac to your Ref CD9SE via USB and control it through either the Kodi web interface or a UPnP app on a mobile device such as BubbleUPnP (Android) or mConnect (iOS). You can also stream from music services such as Qobuz or Tidal to either Kodi or your Pioneer from those apps as well since Kodi and the Pioneer also function as UPnP renderers.
I’ve used Kodi before to turn my Mac mini into a media server and it worked well. If you need any details, feel free to message me.