Thanks guys. Basically I can just connect my external, tell iTunes that my external is my iTunes library, then match? Then unplug? As long as the "copy files to iTunes media folder" option is unchecked it won't make a local copy of the whole file right?
It's a bit confusing when explained I guess.
- Plug in external, add music to local iTunes library
- Match/Upload it all to the cloud.
- Select your entire library in iTunes and select Delete, select "Keep files" and don't tick the "also remove from iCloud" tickbox.
This will make your local iTunes library blank, preserve your files on the external and the music now in the cloud.
Now remove your external drive and add your computer to iTunes Match if it's not already added (I don't remember if iTunes automatically disables match for your computer if you "clean out" the library, it might not). Disabling iTunes Match on your computer
will not delete your music from the cloud.
It will then populate iTunes with your cloud music. Appearance wise you'll see the "download from the cloud" button next to each song but that's about it.