There is nothing mysterious about calculating your average and peak power requirements.
Use this
For example.
Speaker sensitivity 87dB/2.83V/1m. 9ft listening distance.
Average SPL Level 85dB (pretty loud already for home listening - not party loud but loud).
-> Average Power: 2.5 Watts. Yes that’s all.
Now assuming you listen to music (eg classical music) with dynamics of 20dB.
-> Peak SPL 105dB (provided your speakers can even handle this without major distortion)
-> Peak Power 250W at 8 ohm and 500W at 4ohm.
However most modern music has much lower dynamics ca 13dB, heavy metal ca only 6dB. So you need considerable less peak power, ca 50W and 10W respectively.
And ca 105dB is pretty much the limit of many speakers and they already start distorting considerably as the speaker simply isn’t playing nicely at those level. Not even considering your hearing.
So again much less power really needed. (Of course there are always exceptions, especially if you have speakers with less sensitivity or which go down to even 2ohms).