An underpowered amp can damage speakers as well. When the amp goes into clipping, its output can approach a square wave, which has multiple harmonics way up in the sound spectrum. That can damage tweeters, and if pushed far enough, the rest of the speaker drivers.
A high power amp is almost always a benefit, unless you also drive it into clipping. One way to protect speakers is to put a fuse in line. Purists will cry foul about adding the small extra resistance, but really it is fine. Start with 1 amp fuses, fast blow. If the fuse blows too quickly, then up it to 1.25, 1.5, or 2 amps.
Ohms law can help choose the fuse. Watts = I²R. where I is the current rating of the fuse and R is the impedance of the speaker. But, to know at what current the fuse will blow you have to know the characteristics of the fuse itself. Each type of fuse has its own melting point above its rated current, which you can find by looking up the fuse curve on the manufacturer's website.
If that is too much trouble, then remember that speakers are usually rated at RMS or continuous power; sometimes peak power will also be used. However, unless you are playing sine waves all the time (boring
) music's average power will be much lower than RMS.
Emotiva amps are a great buy. I have 2 XPA-5s and a UPA-1 driving highly efficient Klipsch Heritage speakers. There is a readily evident improvement in sound compared to driving the speakers with my Denon AVR. Many people will argue that there is no difference, but what I hear is not a placebo effect - added clarity in midrange. Plus the system has almost unlimited dynamic range now - well into the damaging ears territory.
