As someone who is building a system at the moment with active crosses, its damn difficult to find any power amp with left than 50 watts per channel unless you buy Vellum and build them yourself.So if you put in horns, its over kill. I'm currently leaning to using Fostex 100HT's in my new system, andf the smallest power amp I could find to power the tweets is 34 watts RMS per channel. Luckily with an active system I can turn the gain on the crossover way down to at least get the amp out of that bad power range below 1 watt.
You will need to do that. Many amps cannot run adequately below 1 watt without serious distortion. Of course use a tube amp, you may actually like the qualities of its distortion. I'm using transister amps purchased from ebay.
Eric J.