kuha, wattage is a factor yes... but a speaker can have 10000 watts...and sound like crap, it all depends on the amount of distortion. I would look for an Amp, with the highest line amperage per channel.. Then wattage alone...couple that with decent speaker wire and your all set.
I should add watts are commonly referred to because that is what people understand... generally the higher the wattage the Amplifier can put out the higher the amperage going to each speaker. But this is not always the case.. just read n read
Just my opinion.
G