Too powerful of an amp!?

That's like too much HP under the hood. Only if you can't handle it.

Just don't trade quality for power, which often happens.  Most of the time, even with your less sensitive speakers, you'll be listening under 25 wpc--maybe even under 5 wpc.  I'd recommend spending your money to get the best amp you can get and if you have to pay more for a 500 wpc amp, you'd be better off getting a higher quality 100 wpc amp for the same money.

Jery

Great advice above.  We are all reconciling the following truisms: 

1. Never under power loudspeakers if you can avoid it.  Too little power can damage speakers. 
2. When buying amps, don't forget when you buy a 400W mono block, or the like, that it's the first few watts that matter. 

When an amplifier clips, nasty stuff typically happens to what the loudspeaker gets fed and pushes back.  

When we listen, even at loud volumes, the first 1-8 watts are most of what we use and hear.  A 9 watt tube guitar amplifier will blow you out of the room, compared to these massive wattage amps we see today.  

Sorry, don't mean to confuse you.  It's all good advice above. It's a delicate balance.  Going over with a good quality amp is usually a good thing!

@jbhiller 's advice above struck me wrong until I kept reading.  You won't damage an amp with a low power signal unless it is clipping/distorting.  So buying a low power amp AND turning it up too loud will damage speakers.

Jerry

True @carlsbad2 !  

So very true.  I powered KEF LS50s with a 300B amp! (8 watts)

If you don't listen loud, a low powered amp won't be harmful. The other consideration with a low powered amp is lack of headroom.