These speakers will work very well with your SET amp. The things you want are high efficiency and flat impedance curve, and these speakers have that.

SET amps with no feedback tend to have low damping factors, which translates to relatively high output impedance. The load impedance sets up a voltage divider with output impedance, and if the load impedasnce changes with frequency, then the voltage across the load varies with frequency. This affects the amplitude response. In addition, output impedance interacts with speaker electro-mechanical parameters, and can change the tuning a little bit. So the speaker load is very important to a SET amplifier, more so than higher power amps with higher damping factors.