My 1804 ran my M80s with no trouble in my 3300 sqft room. I would be very surprised if the 1911 doesn't work equally as well, as Adrian mentioned, within limits. Meaning your room isn't huge ( you mention medium but one's medium is different for everyone) and you don't listen at extreme levels all the time.

Jason
M80 v2
VP160 v3
QS8 v2
PB13 Ultra
Denon 3808
Samsung 85" Q70