High power amplifier and small speakers??

Quality, not quantity is what counts.
Some 150 watt amps will sound like junk on any speaker while others will bring out the best in them. What do you have?

The size of the speaker does not matter. High sensitivity speakers can work with small or big amps. Detail will not be lost at lower volumes with a big amp. The quality of the sound will depend on how good the amp is, not the amount of power. In your case you will only be using the first few watts.

It's not the size of the dog in the fight, it's the size of the fight in the dog!

Thanks for your responses. What if you have two amplifiers of the same quality but different power ratings (high versus low)?

For example, Totem Mani-2s are relatively small stand mounts and you better have some real big horsees driving these or they will sound like cow patties, though I have to admit that cow patties do provide difficult impedance and phase angle curves to a partnering amplifier.