I see a lot of variance on people’s amp recommendations for products. It seems to me like a clean 1W into 32Ω is enough to drive the majority of headphones to 120db, which is extraordinarily loud to the point of being unlistenable. Tons of middle-tier desktop amps can handle going over 5W per channel at the same impedance and some even go over 10W. Are these wattages actually useful for anything? What wattage would set you up for any headphone, regardless of budget?
One consideration with power is that headroom is convenient. Nobody probably listens at 120dB peak spl for most music but there’s media like podcasts with low average volume, and significant EQ also means significant negative preamp. 120dB would basically satisfy my wants, 110dB is workable and 100dB peak would make me put artificial gain sometimes. Wattage limits are mostly hit by low impedance, low sensitivity headphones, but high impedance ones are capped by voltage instead.