To Elevick's suggestion, it's great if you are using speakers with high-order crossovers and it will certainly give you the impression of more horsepower and protect your primary speakers, but if you are running speakers with simple first-order crossovers, then using an outboard crossover is going to kill all of the benefits that first-order crossovers bring.
Also, getting back to power generally, you ideally want an amp with a lower continuous power rating (darTZeel, Ayre, the new Rowland 625) as I explained above, but also an amp with a very stiff power supply that can deliver huge amounts of instantaneous power. Such amps, such as the big Naim amp and the CAT JL1 monos, seemingly have the power of a 500 watt Krell, but without the drawbacks.
Also, getting back to power generally, you ideally want an amp with a lower continuous power rating (darTZeel, Ayre, the new Rowland 625) as I explained above, but also an amp with a very stiff power supply that can deliver huge amounts of instantaneous power. Such amps, such as the big Naim amp and the CAT JL1 monos, seemingly have the power of a 500 watt Krell, but without the drawbacks.