Can you create a playlist of items you want to span?
Can you create a playlist of items you want to span? And, then simply drag that playlist to the span window (once you are hooked up to the NAS)?
I've spanned something to a NAS and everything works fine. I'm not away from my home (and the NAS) and was wondering whether I could create a playlist in iTunes of items that I want to span when I get back to home (where I can see the NAS). But, I don't want to take the time to create such a playlist now if it won't save me time when I get home next week (where I can see the NAS once again).
Is this doable? (Forgot to "try it" the last time I was hooked up to the NAS and can't find any discussion as to whether it might work or not.)