Answer one question. Get exactly what you need.
Pick the device at the end of your signal chain. If multiple sources go through one of these, that's your answer.
Every listening lounge signal chain ends the same way — audio into a USB interface, then into a tablet or laptop, then out to the display. Here's exactly what to buy for each starting point.
Most amps and receivers have a REC OUT or TAPE OUT on the back — two RCA jacks usually labeled exactly that. Run a cable from there to a USB audio interface, plug it into your tablet or laptop, and Cueboard has a clean signal.
Every mixer has a REC OUT or BOOTH OUT — sometimes both. Run a cable from there to a USB audio interface into your tablet or laptop. If your mixer has a USB port labeled Audio or PC, you may not even need the interface — plug directly into your tablet or laptop.
Sonos, Bluesound, and every serious streaming player has RCA line outputs on the back. Run a cable from there into a USB audio interface, then into your tablet or laptop.
If you're playing music from a computer, tablet, or phone, Cueboard can run in a browser tab on the same device — no extra audio hardware needed. The only other thing you need is a screen for the room.