Hi,
Why are you hung up on 100 watts?
Consider that you have to double the wattage to double the power in db. So going from 25 watts to 50 watts is +3db of power. But this is
not twice as loud. +10db is approximately twice as loud to us psychoacoustically. So from 25 watts, we would need to get to 50 watts (+3db) then 100 watts (+6db) and finally 200 (250 really) watts (+10db) to perceive it to be twice as loud. Going from a 25 watt amp to a 200 watt amp is literally going from $50 to $1,000. There's more to this, of course, but the idea is to help figure out why you need 100 watts.
Great reading material:
This article discusses the relationship between the decibel(dB) for audio devices that produce sound and how we perceive loudness. Basic audio rules are given to relating to the decibel.
www.audioholics.com
75 watts to 100 watts is virtually meaningless. It's significantly less than +3 db of power. You wouldn't even perceive this most likely.
Instead, I would argue that you should compare your speaker's sensitivity, room size and figure out approximately what range of output you actually need and then shop based on that.
Very best,