what's the best way to bring let's say Netflix streaming into the studio? Is there an affordable box that decodes Atmos to 12 line-level outputs (or AES?)
The easiest solution I know is:
Connect your streaming device (like an Apple TV 4K) via HDMI with a consumer electronics AVR Pre-Amp. (This is an AVR with 12 XLR-Outputs). These models are available from many manufacturers.
The output of the Pre-Amp will be 12 analog line-level XLR signals, that need to be AD-converted feed into your studio infrastructure.
I don´t know of a device that would output directly AES digital signals.
Best wishes, David