A 700 WOPL will rattle the windows at like 25 watts so it's not necessary to double up speakers and risk the amp especially when most preamps have 2 outputs which lets you run another amp and speakers.
Consider getting larger speakers for a larger room.
I didn't realize how much difference it makes until I picked up a pair of JBL L150 Millenniums.
Larger rooms need larger speakers.
Or Dahlquitst DQ-10s do good in a big room and a 700 has more than enough oomph to make them sound good.
I did stack 8 JBL theater surround speakers into line arrays, wired in series-parallel to get 8 ohms and ran them with my 4 fin WOPL 400. it did run warm to the touch but it didn't blow up.