Go to the Pass website and look for yourself: https://passlabs.com/products/amplifiers/x.5/x350.5
The X350.5 - 600 watts
The X250.5 - 300 watts
The XA30.5 - 200 watts
I'm in a 10' x 12.5' room and as much as I liked the sound of the XA30.5, I was sweating. It doesn't even run as hot as the X250.5 or X350.5.
Maybe the heat won't be as confined when you move to the larger room, but right now be ready for the heat.
It's sad, because as much as I really, really liked the XA30.5, the heat made it so uncomfortable that I couldn't enjoy it. Then again though, you may not be as bothered as me by the heat.
Chuck