I think loudness is a fairly broad statement.

A true broad band system than can hold up full power down to say 30 hertz will always sound bigger and not necessarily louder.

I equate loud with a distorted system that is loud because it goes neither loud nor high cleanly. Loud is often not dynamic but compressed.

Conservatavely I at one time used 1300 watts biamped on 4343.

As they say it taskes cubic inches in terms of amp power.

It also depend on the reverberant field of the room.

Ian