I think I mentioned previously that Polk speakers are designed to take large amounts of power. That does not necessarily mean it’s necessary. I agree that something in the 200-300w range should be sufficient if “power-hungry” is truly a thing. That said, since beginning to research amps and speakers, I’ve not seen any evidence presented that potential headroom in an amp... that is to say the potential to deliver more power still than that required to produce the spl you are listening at... creates a better sound.
When picking an amp, and using that calculator, consider that you need about 20db of headroom in most situations. Orchestral music can actually be more demanding, still, than a movie! Movies are designed for that 20dB dynamic peak; there is no standard for a pianissimo flute solo immediately followed by 100 skilled musicians playing FFF! That could easily be a 60dB swing. Regardless, if you look at the sensitivity of your speakers:
1w=90dB, 1meter
2w, 93
4w, 96
8w, 99
16w, 102
32w, 105
64w, 108
128w, 111
256w, 114
Considering that with every doubling of distance, you lose 6dB, you could expect to lose ~9dB at your seat. So theoretically, 256 w producing 114dB @1m, equates to 105dB at your seat, which is reference level dynamic peak.
As you’ve stated, that is louder than you care to listen, however, it also provides the headroom that you want to have at your control.
Until I see a quantification of “power hungry” and what that means for wattage required to make a sound... I don’t accept the argument that your Polks require a 500w or 1000w amp (two different rules of thumb people use).
That said, it is your system. If you want an amp that powerful, go for it.
Personally, I think 256w is fine. Beyond that, you have exceeded the point of diminishing returns and firmly entered the realm of frivolous expenditure.