Soundboard to Zoom H4n: Attenuator or DI Box?

I soon will be recording a live event by (1) taking a feed from the soundboard into the Zoom H4n's inputs, and (2) using the H4n's internal mics to capture the PA mix from the "sweet spot" of the room. I then can mix these tracks together in post.

Regarding the feed from the soundboard into the H4n's inputs: I have read that it is necessary to use either an attenuator, such as the Shure A15AS, or a DI Box, such as the Behringer D120, to "bridge the gap" between a soundboard's professional line-level output (+4dBu) and the H4n's consumer line-level input (-10dBV). As I understand it, both "in between" solutions are also useful for "converting" a line-level output to the H4n's mic-level XLR input.

Are these assumptions correct? And if so, what are the advantages and disadvantages of each approach? Is it better to use an attenuator or a DI Box to get the job done?