There is one consideration not mentioned so far. If you have a high gain amp (not necessarily high power) and a high gain pre-amp, coupled to high sensitivity speakers, you may have to operate the pre-amp at the very low end of its volume control, where there are more likely to be anomalies in channel balance, etc. Also if its a stepped volume control, the steps are typically larger at the low end and it may be difficult to get the "right" volume. Other than that, there is no problem with using high power amp with high sensitivity speakers.
High power amplifier and small speakers??
As a general rule could one say that sound quality is diminished by using a powerful amplifier (150 w/ch into 8ohms) with small speakers (high sensitivity)? Would detail be lost at lower volumes? I am curios because I am planning on upgrading my amp but have small speakers (may upgrade later)/