The drum room wall, insulated and drywalled both sides. Solid core door for access. Double pane thermo windows to be able to see the drummer. The room was built for 2 drum kits, one behind each window.
There is a drum room sub-mixer for dialing in your own playback mix (I took a split off all mics and sent that to the drum room mixer) as well as submixing the drum mics back to the main board in the main room for others to hear the drums as they wish.
When recording, I run mics directly from the drums to the main board bypassing the drum room mixer.