Optimal output range


Hi folks,
Just curious about optimal output range regarding volume levels for amplifiers.I have just moved to a bigger place with a larger listening room. 

So no surprise my 150 wpc SS integrated needs to be turned up higher to be as loud as my 300 wpc SS monoblocks.
The 150 wpc seems to open up more above about 40% volume.
And though I can enjoy higher volume levels in the bigger place, it seems like both amps still need to be kept low. 
Aside from a few short seconds here and there, I haven't cranked up the monoblocks to anywhere near 40% for any length of time.  It's just too loud.  Maybe I can tell if they open up more in a bigger room.

I know engines have certain rpm ranges where they perform better than at other rpm ranges (horsepower, torque, efficiency).Do amps have a certain volume range where they are designed to perform at their best.
Are the monoblocks better suited for a larger room where they can "sing" louder?
hleeid
In addition, there's usually a sweet spot for the preamp volume control, which is normally towards the middle of its range.
If you look at some graphs showing power vs. distortion you will see the sweet spot for the amp when it comes to output. SS state amps generally start at lowish distortion, drop down even lower in the sweet spot, and then rise (eventually steeply) at a given output. Here is an example - look at figure 4.

https://www.stereophile.com/content/pass-laboratories-xa25-power-amplifier-measurements

Generally people say the volume somewhere in the middle of the range is most optimal. But of course this will change depending on the preamp, amp, speakers, etc.