Installing the base was not that difficult.
I put a rolled up table cloth under the end of the speaker to lift it up so that the bolt could align easily. The speaker was raised 3-4" off of the floor.
Here's one of the two bolt holes:

Here's the speaker sitting on the rolled up table cloth. I just peeled the plastic wrap back to install the base. I unwrapped them the rest of the way once they were standing up.

Here's one bolt screwed in part way so that I can install the bolt on the other side.
**The washer is just visible under the bolt head. The washer has some numbers stamped in it on one side. I faced the numbers towards the bolt head so they wouldn't mar the surface of the base when tightened down. This is admittedly meaningless since you'll never see that bottom when in use.**
