Like most integrateds, the 7200 has no sub out, but you can still use a sub with it via the B speaker level outputs. I use mine with no sub, though in a smaller room and it works great. However in a room that size, even with towers, you are going to give up bass extension. The 7200 has plenty of power, but bass is the most demanding aspect of sound and the lower your mains play, the harder the amp needs to work to drive them.
I'd recommend you look at the Mordaunt Short (sister company to Marantz) 906 ($750) or 908 ($1100).