Very smart question from someone who is doing it the right way. I was in the same place as you. I was starting a listening room from scratch and a dealer recommended treating the room first and then working out the equipment. Best advice I ever got.
The dealer worked with Viacoustic and sent my room specs to have recommendations made. Viacoustic came back with a comprehensive, fully modeled schematic to optimize the room. I followed the guidance and was very, very pleased with the results after installing treatments.
Money well spent that gave me confidence that spending hard earned money on electronics will yield the best possible return.
My best advice is don't half-ass the room treatments, get professional help, then enjoy your room. I'm not all that far from you and if you would like a tour of my room hit me up. Good luck and cheers.