So after 7 years, I have finally decided to replace my current system the Logitech Z-5500 with a new speaker system. I thought it is about time to get a serious speaker system for my home theater. My budget is $5000. The current receiver I have my eye on is a second hand Yamaha RX-A3000 for $800. Also I want to get 2 Pioneer SP-C21 one for back and one for front and 2 sets of S-31B-LR-K for front and back. However, I have absolutely no idea for what subwoofer I should get. Just took measurement of the room and it's 19" by 16" so around 5.8 meters by 4.9 meters. Thank you for your time.