Ah, that's ok, I also always wait for the wife and the kids to go out before cranking it up, they'd call me deaf or crazy otherwise. But there is no guy with a Randall next to me, that would rise the bar.
I guess clean headroom comes from the design of the power amp, maybe it's always the poor power supply that makes problems there and the question is if it can supply fast attacks in the lows or if it gets to it's limits then.
When you take a 400w amp for a 200w speaker the supply should always be good enough even when the design is cheap. A solution that works for sure. That does not say that all tiny amps are garbage on the other hand.
Some are crappy, some are decend. Some lie about their power rating, some give a true and fair view.