Hi there, have you seen the quick start section of the manual for this setup? That should get you in the right direction: https://cdn.eventideaudio.com/manuals/h9000/2.1.12/content/quickstart/USBaudiosetup.html#audio-interface
Connecting headphones directly to the H9000 will be tricky and is not recommended without a dedicated headphone amp or something like that. Connecting the analog outputs 1-2 to some studio monitors or something that can handle line level signals will work fine.
Once you have followed the quick start instructions, I would suggest loading up the oscillator algorithm (#13 or #14) in the FX Chains so you can verify which H9000 outputs are being sent to which tracks in your DAW.
The Aggregate device route could also work, once you have that setup you should see the 16 USB I/O of the H9000 available as your send/return channels, along with 2 more output channels from your computers headphone outputs.
Let me know how it goes.
