If you are playing Spotify and iTunes on your receiver now, it will work. If not you’ll need to figure out how to get those streams to your AVR (network, Bluetooth, coax, optical)
The o2 can connect from the rca tape or video out on the receiver. I did this for kicks with my 1610, but it’s not where I listen to headphones.
I haven’t heard the 3490. If you aren’t happy with the headphone amp on it, an external amp is worth trying if this is your primary listening area . The DAC is probably fine.