I use a DTE DR-HD100 with my JVC HD100 camera. I have the Anton-Bauer Dionic 90 powering the camera and would also like to use that to power the Firestore.

I see one option that is made specifically for that purpose - Anton Bauer PT-FS4 Power Tap to Firestore

But I also see this one: Switronix PTFS24 Power-Tap Male to Firestore


The first one is $50, the second is $30. Are they functionally the same? Is "Power-Tap" a standard, and it doesn't matter whether it's from Anton Bauer or from Switronix?

Powertap (or D-tap) is indeed a standard. Switronix makes decent 3rd party accessories that conform to the standard. Your choice should probably be made on which is the best length for your application: 14 or 24".