Welcome!
Moving from headphones to loudspeakers entails a lot. First is the room, hopefully not small or squarish, and hopefully well insulated. Will the room be dedicated to listening/watching so you can set up loudspeakers and listening chair optimally? Do you have the flexibility to move/remove furnishings to make room for subwoofers and room treatments?
Second suggest reading Floyd Toole's "Sound Reproduction" 3rd edition as it's the consummate audiophile guide for explaining how loudspeaker and subwoofers behave in-room. In it you'll learn about the transition frequency (where sound goes from wave behavior to ray behavior), the value of using 4 subwoofers to control inherent in-room bass peaks (that can be +/- 30 dB), and the value of room treatments (mostly bass absorption recommended).
Mid/high frequencies are best produced away from walls, while bass is best produced from corners or along walls, so don't bother with full range loudspeakers. Plus big loudspeakers are harder to sell on when the time comes. And then there's the budget. Good loudspeakers can be had for under $1000/pair. IMO best to avoid the issues of power amps and speaker cables by going with the superior concept of active loudspeakers that use one channel of power amplification per driver and a low voltage/more sophisticated crossover.
