Again, almost any amplifier that will deliver at least 50% more power into a 4 ohm load than into an 8 ohm load will work great. My Lyngdorf SDA-2175 amps are rated at 200 watts per channel into 8 ohms, but a healthy 375 watts into 4 ohms, and my Gold Monitors sound better than any other Gold Monitors I've heard. (The room is well treated, too.)
It's generally easier for a designer to squeeze out a few more dB of sensitivity by using 4 ohm drivers as opposed to the 8 ohm versions of the same drivers, not to mention the fact that a good amp will also deliver more power into a 4 ohm load. In a perfect world, you could be looking at as much as 5 dB more output from the system. That's a difference that's palpable, especially on peaks.
aka TRIAD DUDE
I can tell people who are judgmental just by looking at them...