Help with Setup

Our church is looking to improve our live stream setup. Currently, we have a fairly basic setup. We're running two stationary cameras through OBS on a 2016 iMac. Our sound is run through a Behringer X32. We stream through Facebook Live.

We are wanting to increase production quality a bit. We are thinking about getting the ATEM Television Studio. We can connect our cameras but also run our ProPresenter (presentation) software to broadcast some of the stuff being shown on our screens.

What I'm wondering: would there be a benefit to also purchasing the Blackmagic Design Web Presenter? Is there a benefit to running the stream through that rather than just running it through the iMac to the internet? Is it unnecessary with the ATEM Television Studio? If so, do you recommend pairing the ATEM Television Studio with anything else?

Forgive me for my ignorance, I'm just trying to do due diligence so we make sure our setup is configured properly. We are new to much of this, but we're quick learners.

If you're using two cameras with OBS, it sounds like you already have a capture device. Depending on what it is, you may be able to connect the ATEM program feed to that, and broadcast that to FB through OBS.