2021-07-01: Deprecated. This scenario and the hacks involved likely still work, but I'm no longer using this in lieu of simply organizing and tagging with MusicBrainz Picard and using Plex Media Server instead of iTunes.
Unfortunately storing a TB+ of music is a real challenge on a laptop with only a 256GB SSD. Luckily with lunchy (a launchd wrapper), rsync, automator and a little magic the task is made simpler.
One might want to use this with a Gbps fiber connection and VPN. If you're using a Synology NAS it's entirely possible to configure the VPN, DNS, DHCP, etc directly. Some may prefer however to set up a VPN on the router for better isolation. The latter is my preferred method.