the OP's question was will 300w sound better than 80w given the same db level of listening, amp quality etc.
I think the answers given are illuminating and fairly stated: unless you need the headroom provided by a more powerful amp, one is not likely to hear much of a difference. Caveat caveat caveat, YMMV.
I would just like to echo the OP's line of thinking: for years I always thought the more powerful the amp the better the sound. I think I bought in to the general idea because that's how audio is often portrayed: the more powerful the better. Somewhere along the trail I read an article called "The First Watt". The basic premise being most people listen at modest levels, so who cares how many watts you have if your first watt sounds like crap.
That thought began my journey and search that ends up right where we are now: one only needs as much good quality power (plus some headroom) as you usually listen to. For most of us, that means we don't really need or will ever take advantage of big power amps.
Rational thought says we don't need big power. If you study human beings, we make a lot of decisions on irrational terms. I don't need a big power amp. I surely don't. But that won't stop me from buying one some day when a big check arrives and I find one with the right colored knobs and VU meters on it.
